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Love rainbow desserts? Try making swirled rainbow frosting! This decorating trick is GORGEOUS, and super easy to do. You can make these bright buttercream swirls with your favorite frosting recipe in under 5 minutes!
How to Make Rainbow Swirled Buttercream
Is there anything more cheerful than a cupcake topped with a big, bold swirl of rainbow frosting? Just seeing a group of rainbow cupcakes lined up together never fails to make me smile.
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Rainbow frosting has been popular for years, because it works for so many different events: kids and adult birthdays, showers, spring and summer parties, St. Patrick’s Day and Pride events, and so many other occasions! It can be customized with any colors you’d like, and best of all, it looks complicated but is actually super easy to achieve. Here’s how you do it!
Choosing A Frosting Recipe
The first step to making your rainbow frosting swirls is to prepare your buttercream. For this technique, you can use any white frosting with a pipeable consistency. American buttercream, Swiss Meringue Buttercream, and the Easiest Swiss Meringue Buttercream are all great choices, and if you don’t already have a favorite recipe, there’s a full recipe down below for you!
Avoid This Mistake:
Don’t use canned frosting purchased at the store, because it is too soft to pipe well and won’t make the gorgeous cupcake swirls we’re looking for.
Coloring the Buttercream
Once you’ve made your buttercream, it’s time to color it! Figure out how many colors you’ll be making, and divide it into individual bowls. For standard rainbow cupcakes, you’ll want to do 6 colors total: red, orange, yellow, green, blue, and purple.
What Food Coloring to Use
I strongly recommend using gel food coloring over the liquid food coloring you can buy in a grocery store. Gel colors are more concentrated, so you won’t have to use as much coloring to get a bright, vibrant color. (Bonus: you can hopefully avoid the “food coloring aftertaste” if you use good-quality gel colors!)
I recommend Americolor brand food coloring, or the Wilton ColorRight system. Here are the colors I used in these photos (these are affiliate links):
- Red gel food coloring
- Orange gel food coloring
- Yellow gel food coloring
- Green gel food coloring
- Blue gel food coloring
- Purple gel food coloring
Tip for Red Food Coloring:
It is notoriously hard to get a bright red buttercream color! To achieve this, use a good-quality gel brand, and warm up a small amount (~1/4 cup) of buttercream in the microwave until warm but not hot. Mix a generous spoonful of red gel in with the warm buttercream, then mix THAT into the whole bowl. Starting with this small concentrated red portion helps the color disperse better throughout the batch. Additionally, the color will deepen as it sits, so if possible, mix up your red color the day before you need it so it has time to deepen.
In addition to the food coloring, you’ll want to have the following (these are affiliate links):
Filling the Piping Bag
Your buttercream is made and colored to perfection. Time to get your swirl on! Transfer each color to its own piping bag. (You can substitute a gallon-sized zip-top bag with a hole snipped in the corner, if you’d like.)
Lay out a piece of plastic wrap on your counter. Start by piping a long line of red food coloring on the plastic wrap. Leave a margin of a few inches from the sides and bottom of the wrap. Next, pipe the orange frosting right next to the red:
Continue to pipe the colors in a row on the plastic wrap. Depending on how thick you pipe them, you can either fit one line of each color on the wrap, or repeat the pattern and make 12 stripes. Just make sure you leave a margin and don’t go all the way to the edge of the plastic wrap.
Now, fold the plastic wrap over lengthwise and roll the frosting into a cylinder. Grasp the ends of the plastic wrap in each hand, and twirl it quickly so the frosting is burrito-shaped and the ends of the plastic are tightly twisted.
Fit a piping bag with a large star tip – I like the size of Ateco #849. Snip off one of the plastic wrap “tails,” and insert the frosting cylinder into the piping bag, snipped-side down.
Your piping bag is now ready to go! Give it a little squeeze, because sometimes it takes a minute for all of the colors to come out together.
🌈 More Rainbow Desserts:
- Rainbow Cake with Rainbow Frosting
- Pot of Gold Rainbow Cake
- Rainbow Mousse Cake
- Pastel Rainbow Gelatin Cups
- Rainbow Cake Push-Up Pops
- How to Make A Fondant Rainbow
Rainbow Frosting Swirls
- 4 TBSP milk at room temperature
- 1 TBSP vanilla extract or other flavoring
- ½ tsp salt
- 8 oz unsalted butter at room temperature
- 8 oz shortening can replace with equal amount butter if desired
- 28 oz powdered sugar sifted (7 cups)
- Gel food coloring in rainbow colors I recommend Americolor
- Combine the milk, vanilla extract, and salt in a small bowl, and stir them together to dissolve the salt and set aside.
- Place the butter in a stand mixer fitted with a paddle attachment. Mix for 2 minutes on medium speed, until the butter is lighter in color and creamy. Scrape the bottom and sides of the bowl.
- Add the shortening and the milk mixture, and use a splatter guard over your bowl or place a towel over the top of the mixer to prevent splatters. Run the mixer on low until the liquid starts to incorporate, then turn it to medium until everything is well-mixed and smooth (20-30 seconds). Scrape down the bowl again.
- Keep the towel over the mixer, leaving only a small opening in front, turn the mixer to low, and add the sugar to the bowl in a steady stream. Once all of the sugar is incorporated, scrape down the bottom and sides of the bowl, and turn the mixer to medium-low for 30 seconds to mix the frosting well.
- Divide the frosting equally between 6 bowls. Add a different color of gel food coloring to each bowl and stir well, adding more if necessary until you get a vibrant color. Place each color of frosting into its own piping bag, and snip a 1/2-inch opening in the end of each bag.
- Lay out a piece of plastic wrap about 16 inches long. Start by piping a long line of red food coloring on the plastic wrap. Leave a margin of a few inches from the sides and bottom of the wrap. Next, pipe the orange frosting right next to the red, and continue to pipe each color in a line. Depending on how thick you pipe them, you can either fit one line of each color on the wrap, or repeat the pattern and make 12 stripes. Just make sure you leave a margin and don't go all the way to the edge of the plastic wrap. (If you have extra colors left over, you can do this a second time to make another rainbow piping bag.)
- Now, fold the plastic wrap over lengthwise and roll the frosting into a cylinder. Grasp the ends of the plastic wrap in each hand, and twirl it quickly so the frosting is burrito-shaped and the ends of the plastic are tightly twisted. Fit a piping bag with a large star tip. Snip off one of the plastic wrap “tails," and insert the frosting cylinder into the piping bag, snipped-side down.
- Squeeze the bag for a moment until all of the colors come out together, then your rainbow piping bag is ready! This recipe makes enough to frost 18 cupcakes with large swirls, or 24-28 cupcakes with small single-layer swirls.