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Galaxy Mousse Cakes are almost too pretty to be real! Mini chocolate mousse cakes on a brownie base are covered with a gorgeous glossy mirror glaze that’s swirled to look like the galaxy. They are delicious, edible works of art!
This post is sponsored by International Delight. This year I’m pleased to partner with them to bring you a series of dessert recipes featuring their products.
I can’t believe it’s taken me this long to try my hand at a mirror glaze cake! I feel like I’ve been seeing them on my Instagram feed for about a decade now, although it’s probably only been in the past year that they’ve become really popular. (…on my Instagram feed…and possibly nowhere else…the standards for popularity are pretty low around here.)
If you’re not familiar with mirror glaze, it’s a white chocolate glaze made with gelatin that is poured over cakes—usually mousse or other soft molded desserts—to give them an ultra-shiny appearance, like the surface of a mirror.
You can do SO many cool effects with mirror glazes just by adding different colors, pouring in patterns, or scraping the surface of the cake in different ways. You can create cracks, spiderwebs, tie-dye effects, and so much more. For my first go-round with mirror glaze, I decided to tackle a small subject: THE GALAXY.
*insert epic maniacal laughter here*
Here’s the bad news: this recipe has a lot of steps because there are 3 different components: the brownie base, the chocolate mousse, and the mirror glaze itself. You can skip the homemade brownies and go straight for a box mix, but it’s still going to be quite the time investment in the kitchen.
Here’s the good news: the mirror glaze itself is simple to make, easy to pour and use (what a welcome surprise that was!), and SO FREAKING COOL IN REAL LIFE.
SORRY FOR SHOUTING.
IT’S JUST REALLY COOL.
But I’m getting ahead of myself. First, the innards.
The chocolate mousse is actually sort of a cheater’s version of mousse—no eggs are involved. Instead, it uses gelatin to give the mousse some stability, and I flavored it with International Delight Chocolate Caramel Creamer, which—might I say—I could just drink with a straw, I love it that much. I didn’t get too much of the caramel taste in the finished recipe, but it definitely boosted the chocolate flavor!
(Quick ingredient note: I know International Delight is not available in every country, and whenever I post a recipe with their products, I get a lot of questions about substitutions. So if you can’t find the Chocolate Caramel flavor you can use another flavor, and if you can’t find ID products at all, heavy cream can be used in the mousse instead. Just know that I’m always grateful when you are able and choose to support the sponsors who support SugarHero!)
I knew these would be intensely chocolatey, so I planned to make smaller, mini mousse cakes, both to control portions and for the cuteness factor. We thought these 3-inch spheres were the perfect serving size—enough to satisfy a big sweets craving, but not a ridiculous amount of mousse. And I love how the sphere shape makes them look even more space-themed!
I used this silicone mold to shape the desserts. (You’ll need 2 to make the 10 cakes this recipe produces.) You don’t have to use this one, but I would be sure to pick a mold that’s deep enough to hold both mousse and brownie, smooth on the inside, so the top of the mousse won’t be textured and ruin the mirror effect, and large enough to produce a dessert that’s satisfying by itself. I don’t even know you, but I DO know you don’t have time to make a kazillion bite-sized galaxy mousse cakelets.
Oh, and you DEFINITELY want silicone, as opposed to traditional pans. Being able to flex the mold inside-out to remove the mousse is a must!
The mirror glaze seems intimidating. Believe me, I know. All those Instagram videos have been taunting me for the last year, but I had the fear in my belly. The fear that it would be a long project that would most likely leave my kitchen floors covered in sticky gelatin glaze. The last part was true (because I’m a klutz) but the first part is a lie. Mirror glaze is really not difficult! I hope the video up top will give you an idea of how simple it can be, but if you’re not convinced, I’m doing a Facebook Live THIS Sunday where we’ll make a mirror glaze cake. Follow the SugarHero facebook page and join in the fun!
I went all-out with the galaxy theme, and decorated my mini mousse cakes with swirls of navy, teal, purple, pink, and white colors (which are probably way more colorful than the actual Milky Way, let’s be real.) I finished them off with a pinch of edible silver star sprinkles, and they looked like miniature works of art. Completely edible, totally delicious works of art.
Galaxies aren’t your thing? You can do them all one color, swirl just 2 together, or go for a completely different color scheme than the one I chose.
Mirror Glaze Tips for Success
- Use real white chocolate! I’m sorry, I know it’s much more expensive, but you REALLY don’t want to cheap out and use “white chips” for this one. The palm kernel oil or other substitute fats in the white chips just doesn’t behave the same as real cocoa butter. (It doesn’t taste as good, either!) So you can look for white chocolate chips made with cocoa butter, or buy bars of real white chocolate and chop them up.
- COLD is the name of the game when it comes to molding the mousse. Give the cakes at least 2 hours in the freezer, but know that they might require more depending on your specific freezer. Well-frozen mousse will pop right out of the mold, and soft mousse with leave little bits clinging to the edges, and this rough texture is no good for the mirror glaze. After they’re unmolded, put them back in the freezer so they’re cold when you glaze them! A cold mousse cake is a happy mousse cake.
- NOT COLD is what you want when you serve them. (Sorry, I was trying to be clever but that’s just bad grammar.) I prefer to have them closer to room temperature, because then the brownies are soft and fudgy, and the glaze is very easy to cut through with a spoon. You may not agree…keep tasting them to see what you prefer! 🙂
- Speaking of the glaze…be aware that the finished texture remains sticky (some say rubbery) and it’s unlike most other cake glazes you’ve probably tried. Some people love it, some people peel it off like fondant. And the taste? It just tastes like sweet white chocolate.
- Have fun! Be creative! Play with your food!
🍰 More Cake Recipes You’ll Love
- Chocolate Raspberry Mousse Cake
- Charlotte Royale Cake
- Strawberry Swirl Bundt Cake
- Strawberries and Cream Layer Cake
- Chocolate-Covered Strawberry Cakes
Galaxy Mousse Cakes
For the Brownies:
- 6 oz unsalted butter
- 8 oz semi-sweet chocolate, chopped
- 2 large eggs
- 2 tsp instant espresso powder, optional
- 2 tsp vanilla extract
- 5 oz granulated sugar, (3/4 cup)
- 2.25 oz all-purpose flour, (1/2 cup)
- 1 tsp baking powder
- ½ tsp salt
For the Chocolate Mousse:
- 9 oz semi-sweet chocolate, chopped, or can substitute 1 ½ cups chocolate chips
- ¾ cup International Delight Chocolate Caramel Creamer
- pinch of salt
- 1 packet unflavored powdered gelatin, (.25 oz)
- 2 tbsp water
- 1 cup heavy cream
For the Mirror Glaze:
- 3 packets unflavored powdered gelatin, (.75 oz)
- 9 oz water, divided use
- 10 ½ oz granulated sugar, (1 ½ cups)
- 7 oz sweetened condensed milk, (1/2 of a standard 14-oz can)
- 12 oz white chocolate, chopped, or can substitute 2 cups white chocolate chips
- blue gel food coloring – royal blue, I used Americolor gel food coloring
- blue gel food coloring – sky blue
- purple gel food coloring – electric purple
- pink gel food coloring – electric pink
- Black gel food coloring – super black
- White gel food coloring
To Make the Brownies:
- Line a 9” x 13” baking pan with foil, and spray the foil with nonstick cooking spray. Preheat the oven to 350 F.
- Combine the butter and chopped semi-sweet chocolate in a large microwave-safe bowl. Melt them together in 30-second increments, stirring after every 30 seconds to prevent overheating. Once melted and smooth, let it cool to room temperature.
- Whisk in the eggs one at a time, then whisk in the instant espresso, vanilla, and granulated sugar. Continue to whisk until the texture smooths and thickens and the batter becomes glossy, like pudding. Finally, add the flour, baking powder, and salt, and stir in gently with a spatula until no streaks of flour remain.
- Scrape the batter into the prepared pan and smooth it into an even layer. Bake the brownies for 15 minutes, then remove the pan from the oven and gently rap it on the counter to release any air bubbles. Return it to the oven and bake for an additional 5 minutes (20 minutes of baking total), or until a toothpick inserted into the center comes out with just a few moist crumbs attached.
- Let the brownies cool completely, then use a 2 ¾” circular cutter to cut out 10 brownie circles. If the tops of the brownies are uneven, gently press down on them to flatten them out.
- Place the brownie circles on a covered baking sheet and freeze them until you’re ready to use them.
To Make the Chocolate Mousse:
- Combine the chopped chocolate, International Delight creamer, and salt in a large microwave-safe bowl. Microwave in 30-second increments, whisking every 30 seconds, until the chocolate has melted and the mixture is smooth. Let it cool until it’s slightly warm or room temperature, stirring occasionally.
- While you wait for the chocolate mixture to cool, prepare the gelatin. Whisk together the gelatin and the cold water in a small bowl, and set it aside to let the gelatin absorb the water.
- Whip the remaining 1 cup heavy cream to firm peaks, and set it aside for a moment.
- When the chocolate is at room temperature, it’s showtime! Microwave the bowl of gelatin for 10-12 seconds, until it is melted. Whisk the melted gelatin and chocolate mixture together.
- Fold half of the whipped cream into the chocolate, and once it’s incorporated, gently fold in the remaining whipped cream.
- Make sure your silicone molds are clean and dry. Use a large spoon to fill the half-sphere cavities, leaving about a half-inch of space at the top. Move the spoon around as you fill them to make sure the mousse is evenly distributed and there are no air pockets that will show up later.
- Take a frozen brownie round and press it on top of the mousse, pressing firmly so the mousse comes up around the sides of the brownie. Use a spatula to smooth around the edges so they’re perfectly clean.
- Place the silicone molds on a baking sheet and freeze for at least 2 hours, until VERY firm. (Freezing time may depend on your individual freezer—when in doubt, err on the side of more time!)
- Once frozen, unmold and place each dessert on a small cardboard circle—this will make them easier to transfer later. Keep them in the freezer until you’re ready to glaze them.
To Make the Mirror Glaze:
- Whisk together the gelatin and 4 oz (1/2 cup) cold water in a bowl, and set it aside to let the gelatin absorb the water.
- Combine the remaining 5 oz water, sugar, and condensed milk in a medium saucepan, and place the pan over medium heat. Stir while the sugar dissolves, and bring the mixture to a simmer.
- Once it is simmering steadily, remove it from the heat and add the gelatin (no need to melt the gelatin first—just scrape the big blob out of the bowl!) Whisk the gelatin as the heat from the pan dissolves it, and whisk until it is almost entirely incorporated. A few small pieces of gelatin are fine.
- Add the white chocolate to the pan, and let it sit for a few minutes to soften the chocolate. If you have an immersion blender, that is best to use—just stick it right in the pan and blend until the chocolate is melted and the mixture is very smooth. If not, you can whisk everything together, just try to avoid vigorous whisking that will create a lot of air bubbles.
- Divide your glaze into as many bowls as you want. I find it’s easiest to have a few “base colors” that are larger portions, and a few “accent colors” that are smaller portions. I made 3 base colors, using Americolor Sky Blue, Royal Blue, and a mix of Royal Blue + a drop of Super Black. I made 3 accent colors using Americolor Electric Purple, Electric Pink, and Super White. All you need to do is whisk a few drops of food coloring into each bowl of glaze.
- Let the bowls set until they cool down to about 95 Fahrenheit (35 C). An instant-read thermometer is the easiest way to check this, but if you don’t have one, it should feel barely warm on your fingertip, and be thick enough to coat it. Stir the bowls occasionally as they cool, so they don’t form a skin on top.
- Take the mousse cakes from the freezer. Cover a baking sheet with parchment or waxed paper for easy clean-up, and set small jars or cups on the sheet for the mousse cakes to balance on—try to use ones that are smaller than the base of the cakes, so the glaze can drip down cleanly.
- In a new bowl, pour about 1/3 cup of one of your base colors of glaze, then drizzle the top of it with a few other colors—there’s no rhyme or reason here, so go crazy! After you’ve added all the colors you want, give it a brief stir to swirl everything together, but do NOT swirl too much and muddy the colors! Take this bowl of glaze and pour it over one of the cakes, swirling it around the top to make sure that all the sides are covered. Let the glaze drip down the cake onto the baking sheet.
- If it is dripping quickly and is a very thin layer, it’s too warm and needs to cool down a few more degrees. If it is gloopy and clinging to the cake and barely dripping, it is too cool. You can warm the bowls of glaze BRIEFLY in the microwave (start with 8-10 seconds each) and stir until they’re fluid again, and keep re-warming as necessary while glazing the cakes.
- Repeat the swirling and glazing process with the rest of the cakes. It’s fun to give them all different color schemes so they each look unique. If desired, finish the cakes with a pinch of edible silver star sprinkles. (Any remaining glaze can be saved and used on a different cake within about a week or so. Make sure it stays covered tightly with plastic wrap so it doesn’t form a skin and dry out.)
- Let the cakes sit for about 15 minutes, until the glaze is semi-set, then transfer them to small plates. Chill for an additional 10-15 minutes until the glaze is full set.
- I actually prefer to eat these when they’re closer to room temperature, so the brownie layer is softer, but that’s not everyone’s preference, so do what tastes best to you. Enjoy!
Our recipes are developed using weight measurements, and we highly recommend using a kitchen scale for baking whenever possible. However, if you prefer to use cups, volume measurements are provided as well. PLEASE NOTE: the adage “8 oz = 1 cup” is NOT true when speaking about weight, so don’t be concerned if the measurements don’t fit this formula.Click here to learn more about baking measurements and conversion.
Where can I get the silicone mold?
Hey Linda, I actually got them off of amazon. Here is the link https://amzn.to/2DbpdUj Thanks!
Hello, I am from Holland so pardon my English. Do you have soms tips for me, I want to use agar agar instead off gelatine.
I am making them for a children birthday party and not all children are allowed gelatine . Or maybe something else than agar agar, if hou have an idea. thank you.
Hey Patricia, unfortunately I have never tried it instead of Gelatin so I wont have any tips however I would love to hear back on how it goes if you end trying it out. Thanks so much!
Amazing recipe! Thanks 🙂 the mirror glaze was indeed not so difficult. I was wondering, if I prepare extra glaze, can I keep it in fridge and then melt it again?! for how long? thanks Martina
I wish to make these ahead of time can they be frozen without the chocolate on top until I am ready to use them
Hey Tina, Yes that is exactly how to do it! It should work great. I would love to hear how it goes, and see pictures!
Hey, we don’t have international demight creamer here in France. What can we use instead?
Hey Caroline, You can use heavy cream or whipping cream. Either one should work great! Thanks so much, I would love to see pictures.
I made the mirror glaze and it came out tacky and rubbery, what did I do wrong?
Hi Evonne, As mentioned in the post, the finished texture of the glaze is somewhat sticky and rubbery. This is due to the gelatin in the glaze, and it’s just the nature of all mirror glazes. Some people like it, and some people just peel it off like fondant before eating the cake.
thank you for taking the time to answer my question.
Can you freeze the dessert with the mirror glaze?
Hey, I can’t say for certain I haven’t tried it myself. My concern would be the texture of the mirror glaze and the condensation that may come while it defrosts. Again I can’t say for certain though so if you give it a try I would love to hear how it goes! Thanks so much!
Hi! So I am planning to make those for my OH birthday, instead of a cake (with cupcakes’ toppers saying “Happy Birthday” and “Reach for the Stars”).
I made a trial two following your recipe.
Now, as for the mousse (brownie and mirror glaze came out perfect and super yummy!) I added heavy cream instead of ID (couldn’t find it here in UK), and about 1g of gelatine.
The mousse came out not like mousse at all. It tastes more like chocolate gelly (but more rubbery). Where did I go wrong?
Hi Sylwia, Substituting the cream for ID shouldn’t be a problem at all, and as long as you used a 1:1 ratio I can’t see why that would cause any issues. From the way you describe the texture, it sounds like there was way too much gelatin in the mix. I’m curious about the amount and type of gelatin you used. Was it gelatin powder or leaf gelatin? If leaf gelatin, what strength was it, and how did you reconstitute it? I know that gelatin in other countries can differ greatly from place to place, and I suspect a difference in type and strength of gelatin was the culprit. I’d love to help you troubleshoot so please let me know about the gelatin and we’ll get this figured out!
Thanks a lot for a quick response!
I used Heavenly Delights Beef Gelatine Powder.
I used about 1g (as using metric measurements for 2 servings – 2 mousse cakes), and taking that 1/4oz is about 7g I divided it by five. Could probably say I used about 1.3g to be exact.
All the rest I used as the recipe measurements suggested.
Thank you a lot for your help!
The cake was delicious. I wonder if you could reduce the gelatin to make the glaze less rubbery?
Hi Debra, I’m guessing you can play around with it a little bit. I’d be hesitant to reduce it by too much, since the gelatin is what gives it its body and shine (otherwise it would just be a white chocolate ganache). But there might be some flexibility and a middle ground you can find–please report back if you come up with a recipe that you love!
My glaze was dull in the morning. What did I do wrong?
Hey Christine, I am so sorry to hear you had some trouble with it! I haven’t had that problem, honestly it’s kind of hard to trouble shoot without more detail. I hope it still tasted good! If you wanted to send an email with more details I would love to help trouble shoot!
I would like to make these ahead of time including the glaze, how long can I keep them in the refrigerator without the glaze getting dull?
Hey Wietske, I am so excited for you to make these! With these cakes they can be made a few days in advance. The thing you will want to be aware of is that the glaze tends to become more chewy the longer they are exposed to air-even in the refrigerator. I would try and keep them in an air tight container and cover them with plastic wrap without putting it directly on the glaze as you won’t want to ruin it. I would say two to three days should be fine to make it ahead of time, the closer you can to serving it is best dependent on your time of course seeing as the chewiness of it is limited. Another thing to note is that usually people will even peal off the glaze when eating, like with fondant. I hope that helps, I would love to hear back after you have made them. If you have anymore questions don’t hesitate to ask or even shoot me and email! Have fun!
I’ d like to make this, but I don’t want to use a coffee creamer. Do I just increase the heavy cream by that amount?
Hey Elizabeth, That is exactly right. You can just swap it out for the same amount of heavy cream! Excited for you to make these, I would love to hear how it goes. Have fun!!
Elizabeth, these look so cool! I love baking and I’m dying to try these, but I’m new to this type of dessert, so I’m hoping you can answer a few questions. I won’t be able to serve them right away. I might have to make them the day before. Can they be made ahead, and if so, should they be stored frozen? How long should I thaw them at room temperature before serving? (assuming we’ll eat them at near-room temperature, like you prefer) And if there are some left over afterward, can they be refrozen to serve another day?
Thanks very much!
Hi Robert, I am so excited for you to make these! With these cakes they can be made a few days in advance. The thing you will want to be aware of is that the glaze tends to become more chewy the longer they are exposed to air-even in the refrigerator. I would try and keep them in an air tight container ( in the fridge) and cover them with plastic wrap without putting it directly on the glaze as you won’t want to ruin it. I would say two to three days should be fine to make it ahead of time, the closer you can to serving it is best dependent on your time of course seeing as the chewiness of it is limited. Another thing to note is that usually people will even peal off the glaze when eating, like with fondant. I would think a few hours before serving should be fine to thaw, I would thaw them in the air tight container. As for freezing extra I haven’t tried that myself. My concern would be the texture of the mirror glaze and the condensation that may come while it defrosts. Again I can’t say for certain though so if you give it a try I would love to hear how it goes! I hope that helps, I would love to hear back after you have made them. If you have anymore questions don’t hesitate to ask or even shoot me and email! Have fun!
I am looking to make these but I would like to know the correct size molds for the mousse?
Hey Jennifer, I am so excited for you to make these! I will share the link with you of the molds I used for mine. https://amzn.to/398KGJg If you have anymore questions don’t hesitate to ask! I would love to hear how it goes when you give them a try! Thanks!
Thank you so much Delaine! 😀
My mousse cakes turned out PERFECTLY. The directions were very easy to follow and gave me the same result as Elizabeth (which is rare with online recipes!). These are so delicious, thank you for posting! Definitely going to need to make more soon!
Savanah I am so thrilled to hear that! Thank you for sharing and I’m so glad they worked out for you. 🙂
what material can be replaced with
International delight chocolate caramel creamer
Hi! Milk or half-and-half is a great replacement.
I have used this recipe so many times it isn’t funny. Typically I forgot the mirror glaze and just do a hard chocolate shell and I will put a strawberry or mixed berry coule in the shell first,then the mousse, then the brownie and it works wonders as long as after the freezer they have a second to sit out. Love this! Love love
Oh my gosh that sounds amazing!!! I wish I could see pics of the finished product. Thank you for sharing your ideas and I’m thrilled to hear you enjoy the recipe!
Thanks For Sharing this amazing recipe. My family loved it. I will be sharing this recipe with my friends. Hope the will like it.
Thank you for your feedback, Ashok! Let us know what your friends think of the Galaxy Mousse Cakes!
Hi! I tried the mirror glaze today but they turned out completely see through. Could you tell me what have I done wrong
I’m sorry you had trouble with this recipe. I haven’t had the glaze turn out see through before. My best guess is that something might have been measured wrong. Happy to help you troubleshoot if you want to send me an email at email@example.com
We don’t have Chocolate Caramel Creamer in New Zealand. Can you please recommend at alternative ingredient.
Hi Sara! You can substitute with an equal amount of heavy or whipping cream!
I made 50 of these little beauties for my son and daughter-in-law’s wedding rehearsal dinner. They not only looked beautiful, but tasted amazing too! Thank you for the recipe and detailed instructions!
50!? Wow you’re AMAZING! I hope they were a hit! Thanks for sharing 🙂
brownie recipe was delicious, so was the chocolate mousse. I was not a fan of the glaze. It was too sticky and just tasted sweet – nothing special and a pain in the neck to manipulate. In the future, I’ll stop with the first two steps!
Hi Ingrid! I am so glad you enjoyed the brownie and chocolate mousse. Thank you for your feedback!
Will the frozen mousse, with brownie bottom, release without sticking to the paper if I use paper cupcake liners instead of the molds? I want to make this for my book club that is happening in just a couple of days and there’s not enough time to order and receive the proper molds! Thanks!
Hi Kathy. I’ve never thought of trying it that way before. I would assume that if the mousse is well frozen, you should be able to peel the paper off fairly easily. It will change the shape a little but they will still taste great for your book club friends! Let us know how it turns out. Good luck!
Your mousse recipe is FANTASTIC! Although mine ended up looking exactly like upside down cupcakes, they were amazing! The paper cupcake liners peeled off the mousse easily. Everyone absolutely loved them. I sprinkled colored sanding sugar on top since I didn’t use the mirror glaze.
That’s AWESOME! I’m so glad they turned out so well for you. Yeah for being a SugarHero!
Can I freeze the brownie/mousse cakes a day or 2 before I make/use the glaze? I’m wondering because i don’t know how the gelatin will react in the mousse when freezing overnight
Hi Kelsie! Great question. You can definitely freeze this a day or 2 in advance. Just keep in mind that the mousse will dry out a bit and the texture gets less appetizing with time. Try to keep it well-wrapped or put a lid over the pan so that it doesn’t dry out. Thaw overnight in the fridge the day before you plan to eat it. Glaze it once thawed on the the day you plan to eat it. Happy Baking!
Hello I’m going to try this recipe for my nephews birthday. I’m wondering will they fit on top of cupcakes after making them.
Hi. The molds have a diameter of 3.15 inches. Regular cupcakes have a diameter of 2.25 inches and jumbo cupcakes have a diameter of 3.5 inches . . . so I would say they’d be too big for a regular cupcake but could work for a jumbo sized cupcake. The jumbo size will be slightly larger than the galaxy mousse cakes. If the exposed area of the cupcake bothers you, you could always add a ring of buttercream. Or, you could try making the jumbo cupcakes with less batter so that the top diameter is slightly smaller. I hope that helps. I’d love to see how they turn out! Happy baking.