This beautiful unicorn cake is enchanting to behold, but there’s a sweet surprise inside too: rainbow layers of cake. While it’s certainly magical, it’s not as difficult as you might think to pull off, and it will undoubtedly delight anyone you make it for. For detailed decorating tips, see the author’s article here. And if you need one, here’s a recipe for the Simple Syrup called for in the cake.

Special Equipment:

  • – Kitchen scale
  • – 8-inch round cake pans (at least two)
  • – 2 large heavy-duty pastry bags fitted with a large tip of your choice
  • – Offset spatula (for smoothing frosting) or bench scraper
  • – Cake stand (at least 10 inches in diameter)

Taste even more of the rainbow with our Funfetti Cake Milkshake recipe, and Joy the Baker’s Happy Birthday Pancakes recipe.

  • Yield: 8 to 10 servings
  • Difficulty: Medium
  • Total: 4 hrs 
  • Active: 2 hrs

Ingredients (19)

For the cake:

  • 2 1/2 cups all-purpose flour
  • 1 1/2 cups granulated sugar
  • 1 teaspoon baking soda
  • 1 teaspoon baking powder
  • 1 teaspoon salt
  • 1 cup canola oil
  • 3/4 cup full-fat plain yogurt (not Greek)
  • 3/4 cup water
  • 4 large egg whites
  • 2 teaspoons vanilla extract
  • Food coloring (red, orange, yellow, green, blue, purple), about 4–5 drops of each color for each cake layer
  • 1 cup simple syrup

For the frosting:

  • 3 sticks unsalted butter, at room temperature
  • 4 cups powdered sugar
  • 2 tablespoons whole milk
  • 1/2 teaspoon kosher salt

For decorating:

  • ice cream cone, fondant, edible glitter, gold luster dust, sprinkles, candy, and colored frosting


To make the cake:

  1. Preheat the oven to 350°F. Prepare 8-inch round cake pans by lightly greasing them with butter or cooking spray and dusting with flour, knocking the pans to remove the excess flour. For an extra measure, insert a round of parchment paper to ensure that the layers come out of the pan cleanly.
  2. In a large bowl, whisk together the flour, sugar, baking soda, baking powder, and salt. Make a well in the middle of the flour mixture and add the oil, yogurt, water, egg whites, and vanilla extract. Stir the batter until the batter is smooth. Be careful not to overmix.
  3. Using a kitchen scale, weigh the batter. Divide the batter into six equal-sized portions and distribute into six bowls. To each bowl, add 4–5 drops of one food coloring and stir gently with a spoon to fully incorporate the color.
  4. Working with however many cake pans you have, fill the pans with one batter color and shake to distribute the batter to the edges. Knock the bottom of the pan against the counter to send any remaining air bubbles to the top. Bake the cake layers for 10–12 minutes, or until the tops are slightly browned. Brush with a thin layer of simple syrup and transfer to a cooling rack and let cool completely. Wash the pans in cool water and repeat the process with the remaining color layers.

To make the frosting:

  1. Combine the butter and 2 cups of powdered sugar in a stand mixer and mix on low until smooth. Add the remaining powdered sugar, milk, and salt, and gradually increase the speed until the frosting is fluffy, about 5 minutes. If the frosting is too stiff, add 1 tablespoon milk until the desired consistency is reached.
  2. Fill two large pastry bags (fitted with a large tip) with icing and keep one bag of icing in the fridge until ready to use.

To assemble and frost the cake:

  1. Line the edges of the cake stand with small strips of parchment paper to protect the surface from icing. Add a small amount of frosting to the middle of a cake stand and begin layering the cake in a rainbow pattern, starting with the purple cake and stacking in a rainbow pattern up to red cake. These layers should be fairly flat, as a small amount of batter was used, but if the layers seem too round on the tops, shave some cake off the layer using a long serrated knife or cake leveler. Rounded layers will make this cake difficult to stack.
  2. Spread one layer of the cake with roughly 1/3 inch of frosting and repeat with the remaining cake layers. Press the top of the cake gently to secure it. (It’s okay if some frosting comes out on the sides.)
  3. Cover the whole cake with a thin layer of frosting, creating a crumb coat layering. Don’t worry about the cake looking perfect at this point; that’s what the other frosting bag is for.
  4. Let the cake chill in the fridge for at least 1 hour. Clean your work surface and set up your decorating station.
  5. When the cake has chilled, take it out of the fridge and cover it with the remaining frosting. Use an offset spatula or dough scraper to smooth out the frosting. Run the spatula or scraper under hot water to clean off excess frosting buildup.
  6. Let the cake chill another hour in the fridge. Carefully slide out parchment liners to expose the outer rim of the cake stand, and clean off any excess frosting.
  7. Decorate with unicorn horn, mane, ears, and any extra decorations to complete the look. Click here for more tips.

Reprinted with permission from Unicorn Food © 2018 Rachel Johnson. Published by Sterling Epicure. Photography by Rachel Johnson.