Preheat the oven to 350 degrees Fahrenheit. Line two 7-inch cake pans with parchment paper and spray the pans with nonstick cooking spray.
Place the flour, sugar, baking powder, and salt in the bowl of a large stand mixer fitted with a paddle attachment. Mix them on low speed until well-combined. Add the milk, oil, butter, and vanilla to the mixing bowl and once it’s incorporated, raise the mixer speed to medium-high and beat for 2 minutes.
Scrape down the bottom and sides of the bowl, then add the 2 eggs and beat for 2 minutes more on medium-high speed. Scrape the bottom and sides of the bowl once more.
Divide the batter evenly between the two pans. Bake at 350 for 25-30 minutes, until a toothpick inserted in the center comes out clean and the top springs back when lightly pressed. Let cake cool on rack completely.
To make the rose whipped cream:
In a small bowl, whisk together the powdered gelatin and the cold water, and let it stand until the gelatin absorbs the water. Once absorbed, microwave the bowl for 10-15 seconds, until the gelatin melts. For this recipe, it should be melted but barely warm—certainly not hot. Let it cool if it is too warm.
Microwave 1/4 cup of cream for 10-15 seconds, until it is room temperature. Whisk the room temperature cream into the gelatin and set aside for a moment.
In the bowl of a large stand mixer fitted with a whisk attachment, add the remaining 2 cups of cold cream and the sugar. Whip the cream with the sugar until it starts to thicken. Pour in the cream and gelatin mixture, and continue to beat until the cream is stiff. Be careful not to overwhip the cream and cause it to separate.
Add 4 teaspoons of rose water and a drop or two of pink food coloring, if desired, and mix everything together. Taste the whipped cream and add another teaspoon or two of rose water if the flavor isn’t strong enough. Use immediately.
To make the candied rose petals:
Carefully pull the petals off of the roses and discard any that are damaged or tiny. Whisk the egg white until it’s foamy. Place the sugar in a shallow pie tin.
Use a small, clean, food-safe paint brush to paint a petal with egg white. Hold it over the sugar in the pie tin and sprinkle a layer of sugar on the petal. Tap off any excess, then place it on a wire rack to dry. I found it was easiest to paint 4-5 petals at a time and then sugar them, instead of doing them each individually. After all of the petals have been sugared, let them rest for at least 2-3 hours until they’re dry. (The drying time will vary depending on humidity.) They can be done several days in advance and kept at room temperature.
To assemble the cake:
Carefully slice each cake in half so that you have four rounds. Place one round on a cake cardboard or plate, and top it with about a cup of rose whipped cream. Use an offset spatula or knife to spread the cream evenly on the cake round. Top the cream with a third of the fresh raspberries, keeping them away from the edges of the cake.
Press a second cake round on top, and repeat layering the cream and raspberries. After all the cake layers are added, spread the remaining cream over the top and sides of the cake. The cream will be covered by rose petals, so it doesn’t have to look pretty, but try not to have any bare patches, since the petals will need something to adhere to. Refrigerate the cake for 30 minutes to firm up the cream.
To decorate the cake, press a layer of petals along the bottom edge of the cake, angling them downward slightly and making sure that the edges touch. Press the top of the petal firmly into the whipped cream so it adheres. Add a second layer above the first, overlapping it slightly. Repeat, working your way up the cake until you reach the top. For the top of the cake, start with a ring of petals along the outside edge and work inward. Cluster a few petals together at the center, so that the cake looks like an open flower from above.
Refrigerate the cake until you’re ready to eat it. Remove the petals before eating. Store leftovers in an airtight container in the refrigerator for up to three days.
This recipe makes a 7-inch cake, which is not a typical size. Because the flower petals add so much volume, I wanted to make the cake more petite. (Plus, 7 inches is just more manageable for my small family.) You can make a 9-inch cake by multiplying all quantities by 1.5. (So, for instance, you would multiple the 1.5 cups of flour in the cake by 1.5 to yield 2.25 cups of flour.) Also, I know I said I kept things simple, but I couldn’t resist making a little tweak to the whipped cream by adding a bit of gelatin. This stabilizes it and helps it to keep its shape for a longer time and in warmer temperatures. If you aren’t worried about long-term stability you can skip this step, or if you want a cake that can withstand hours at room temperature, or serious transportation, consider replacing it with rose-flavored buttercream instead.