Rainbow Unicorn Cake | Recipe and How-To

Rainbow Unicorn Cake has been growing in popularity and for very good reason. I mean rainbows and unicorns? How could you go wrong? And may we suggest serving this cake with ice cream to put it over the top?

The rainbow layers of this cake may take a little extra effort which is why you want your entire process to go as smoothly as possible. Check out our cake tips article before you start greasing pans. We also recommend checking out unicorn cake kits at your favorite craft store to make the ears and horns process a breeze.

Recipe Source

Instructions

WHITE CAKE BATTER

  1. Grease the 5 round cake pans and set aside.
  2. In a large mixing bowl, combine the all-purpose flour, baking powder, baking soda, and Kosher salt. Set aside.
  3. Preheat the oven to 325 degrees F.
  4. In a large mixing bowl, beat butter with a handheld electric mixer for about 30 seconds. Add the granulated white sugar and 1 teaspoon pure vanilla extract. Beat until combined. Add the egg whites gradually, one at a time, and beat well after adding each one.
  5. Add the flour mixture and buttermilk alternately to the butter mixture gradually. Mixing well after each addition. Add the batter evenly to each of the 5 baking pans.
  6. Add drops of the gel food coloring to the 5 cake pans and gently stir to combine. (Alternately, you can mix the colors in separate bowls if you don’t want to mix them in the cake pans.)
  7. Bake for 17-20 minutes, rotating halfway during the baking time.
  8. When the cake layers are done, cool on a wire rack for 5-10 minutes before removing from the pans on a wire rack to finish cooling completely. Make sure the cake layers are completely cool before frosting.

BUTTERCREAM FROSTING

  1. In a stand mixing bowl, add unsalted butter and beat for about 30 seconds.
  2. Add vanilla and milk, mix until combined.
  3. Gradually add the confectioner’s sugar, 1/2 cup at a time. Combine completely before each addition. Make sure the frosting is completely smooth before mixing gel food coloring in.
  4. Divide the frosting in half. Half will be used for frosting the cake base and half will be further divided into the colors for decorating the unicorn mane.
  5. Divide the buttercream frosting into 3 equal bowls (or however many colors you wish to do). Add gel food coloring, mix until the color is even. Add each bowl of frosting into piping bags with desired frosting tips. Set aside until ready to decorate.

ASSEMBLING THE UNICORN RAINBOW CAKE

  1. On a rotating cake stand, add a cardboard cake circle, add the first layer (red), add a little frosting to make a thin layer between the cake layers, add the 2nd layer (orange), repeat with yellow, green and purple cake layers. Use the remaining white frosting to frost the outside of the cake using an offset spatula and cake smoothing comb or bench/dough scraper. To get a smooth surface, you may need to refrigerate the cake before putting the final white layer on, depending on the temperature of the room you are working in.
  2. Add the unicorn horn cake topper, the eyes and the ears. (the unicorn cake topper that I use is linked in the recipe card below).
  3. Now the fun part! Pipe the 3 frosting colors with tips to make the mane and forelock of the unicorn.
  4. Add sprinkles to the piped flowers on the mane and forelock of the unicorn cake.
  5. When the decoration is done, allow the cake to firm up in the refrigerator before serving.
Prep, Baking and Decorating: 2 hours 40 minutes
12 large slices

Ingredients

WHITE CAKE BATTER

  • 4 large egg whites (room temperature)
  • 2 pouches of Good Measures AP Flour
  • 1 teaspoon baking powder
  • 1/2 teaspoon baking soda
  • 1/2 teaspoon Kosher salt
  • 1/2 cup unsalted butter
  • 1 3/4 cups granulated white sugar
  • 1 teaspoon pure vanilla extract
  • 1 1/3 cups buttermilk
  • 5 colors of gel food coloring (I use purple, green, yellow, orange and red)

BUTTERCREAM

  • 1/2 stick unsalted butter
  • 1 teaspoon pure vanilla extract
  • 4 cups confectioner’s sugar
  • 1/2 cup whole milk

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