overhead shot of the rainbow cake, with two slices cut out and on plates next to it
Print Recipe

Rainbow Cake

The recipe written below yields one batch of cake batter (two 9" round cakes) and one batch of frosting. To make this same rainbow cake, you will need three batches of cake batter, and 3 batches of frosting.
Prep Time15 mins
Cook Time30 mins
Total Time45 mins
Course: Dessert
Keyword: cake, rainbow

Ingredients

This recipe makes 1 batch of batter - two 9" round cakes (you'll need 3 batches for the rainbow cake)

  • 3 cups all purpose flour
  • 1 tbsp baking powder
  • 1/2 tsp salt
  • 1/2 cup unsalted butter
  • 1/2 cup vegetable oil
  • 1 1/2 cups granulated sugar
  • 4 eggs
  • 1 tbsp vanilla extract
  • 1 1/4 cups buttermilk
  • Red, orange, yellow, green, blue and purple food colour

This recipe makes 1 batch of buttercream (you'll need 3 batches for the rainbow cake)

  • 1 cup butter
  • 3-4 cups icing sugar
  • 2 tsp vanilla
  • 2-3 tbsp heavy cream

Instructions

For the Cake

  • Pre-heat your oven to 350°F. Grease and flour two 9 inch round cake pans.
  • In a medium sized bowl, whisk together flour, baking powder and salt. Set aside.
  • In the bowl of a stand mixer, beat together butter, vegetable oil and sugar until creamy. 
  • Add the eggs to the butter mixture, one at a time, beating well after each addition.
  • Stir in the vanilla extract.
  • Alternate adding the dry ingredients and the buttermilk in several additions, stirring until just combined after each addition (1/3 flour, 1/2 milk, 1/3 flour, 1/2 milk, 1/3 flour). 
  • Divide the batter in half. Tint each half with a different colour of food colouring and then pour into the prepared cake pans.
  • Bake for 30-35 minutes, or until a toothpick inserted into the centre comes out clean.
  • Allow the cakes to cool in their pans for about 10 minutes, before flipping onto a wire rack to cool completely.

For the Frosting

  • Beat the butter on high speed of a stand mixer until smooth and creamy.
  • Add the icing sugar, 1/2 cup at a time, beating well on high speed after each addition.
  • Beat in the vanilla extract.
  • Beat in the cream. If the frosting is too firm, beat in more cream 1 tablespoon at a time. If the frosting is too soft, beat in an extra 1/4 cup of icing sugar, until your desired consistency is reached.

Notes

Vanilla Cake recipe from Sugar Spun Run.