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Rainbow Birthday Cake | An impressive rainbow frosted cake that is perfect for any anniversary, birthday or special occasion. A classic vanilla cake recipe is finished off with multi-color buttercream frosting!
5 from 2 votes

Rainbow Birthday Cake

This rainbow decorated cake is a perfect addition to a birthday party. 

Course Dessert
Cuisine American
Prep Time 45 minutes
Cook Time 30 minutes
Total Time 4 hours 15 minutes
Servings 24 servings
Calories 724 kcal


Buttermilk White Cake

  • 2 c. butter melted
  • 4 c. sugar
  • 6 eggs
  • 2 t. vanilla extract
  • ½ t. almond extract
  • 2 ⅔ c. white rice flour
  • 1 ⅓ c. tapioca starch
  • 2 t. xanthan gum
  • Or 4 c. all purpose flour instead of the above 3 ingredients
  • 2 ½ t. baking powder
  • ½ t. salt
  • 1 ⅓ c. buttermilk

Buttercream Frosting (multiply recipe by 2 ½)

  • ½ c. butter
  • 6 c. powdered sugar
  • 1 egg white
  • 3-4 T. milk
  • 2 t. vanilla clear
  • ½ t. salt
  • Food coloring if desired (first batch (1x above recipe) all white for crumb coating, second batch (1.5x above recipe) for rainbow colors)

Piping Tutorial:

  • 4-6 piping bags
  • 4-6 couplers
  • 4-6 size 12 round piping tips


For the Buttermilk White Cake:

  1. Preheat oven to 350 degrees.
  2. If you have a bowl that fits at least 12 cups of ingredients, go ahead and make this batch as the ingredients are listed above for a 4-layered cake. However, if you do not, halve the ingredients and make two batches. (Half of ⅓ c. = 3 T.+1 t. )
  3. Combine butter and sugar in a large bowl of a high speed mixer. Mix for 2 minutes on medium speed.
  4. In a separate bowl, combine white rice flour, tapioca starch, xanthan gum, baking powder, and salt. Add in about 1 c. of dry ingredients to the butter/sugar bowl. Mix for 30 seconds.
  5. Add eggs, one at a time, mixing well after each addition. Add in vanilla and almond extract.
  6. Add remaining dry ingredients and buttermilk alternatively, starting and ending with dry ingredients. Beat for an additional minute to make batter light and fluffy.
  7. Fill four well-greased 9-inch round cake pans with even amounts of cake batter. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
  8. Let cool for 5-10 minutes before flipping out.

For the Buttercream Frosting:

  1. Cream butter, 2 c. powdered sugar and egg white in the bowl of an electric mixer.
  2. Alternatively add 1 c. sugar and 1 T. milk until all sugar is added.
  3. Add in vanilla, salt and food coloring, if desired.

For the Cake Prep:

  1. Prep your cake for the rainbow icing instructional video by using the first batch of frosting. Place the first layer down, ice the top with a ¼- ½ inch layer of frosting and repeat with the remaining 3 layers.
  2. Trim any uneven edges around the cake and finish the cake prep by applying the remainder of the frosting on the sides of the cake.
Nutrition Facts
Rainbow Birthday Cake
Amount Per Serving
Calories 724 Calories from Fat 189
% Daily Value*
Fat 21g32%
Saturated Fat 13g81%
Cholesterol 95mg32%
Sodium 227mg10%
Potassium 62mg2%
Carbohydrates 131g44%
Sugar 97g108%
Protein 3g6%
Vitamin A 695IU14%
Calcium 30mg3%
Iron 0.5mg3%
* Percent Daily Values are based on a 2000 calorie diet.