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Rainbow Cake
4.6 from 50 votes

Rainbow Cake

The Rainbow Cake features multiple vibrant layers of colored cake baked individually with a classic vanilla batter made from flour, sugar, eggs, oil, and milk. Each layer is tinted with food coloring to create a rainbow effect when stacked. The cake is assembled with a creamy buttercream frosting that incorporates butter, powdered sugar, cream, and vanilla. The layers are baked separately to achieve even colors and textures with a tender crumb and balanced sweetness.

Prep Time
1 hr
Cook Time
40 mins
Additional Time
10 mins
Total Time
1 hr 50 mins
Servings: 12 servings
Calories: 1440 kcal
Course: Dessert
Cuisine: American

Ingredients

For the Rainbow Cake Layers:
  • 5 cups all-purpose flour (600g)
  • 3 cups granulated sugar (600g)
  • 1 tablespoon baking powder
  • ½ teaspoon baking soda
  • 1 teaspoon salt
  • 6 egg room temperature, large
  • 1½ cups vegetable oil (360ml)
  • 1½ cups milk 360ml, whole
  • 1 tablespoon vanilla extract
  • Food Coloring (red, yellow, blue, green)
For the Buttercream:
  • 2½ cups butter softened (565g, unsalted
  • ½ teaspoon salt
  • 10 cups confectioners’ sugar (1200g)
  • ½ cup cream room temperature (120ml)
  • 2 teaspoons vanilla extract

Instructions

For the Rainbow Cake Layers:
    Cup of Yum
  1. Preheat the oven to 350F. Grease two or three 8-inch round cake pans with baking spray or butter. Line the bottoms with parchment paper.
  2. In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, and salt.
  3. In another large mixing bowl, combine the eggs, vegetable oil, milk, and vanilla. Whisk until well combined. Pour into the flour mixture and whisk until combined.
  4. Divide the batter among 6 mixing bowls. Color each batter with food coloring to make red, orange, yellow, green, blue, and purple batters. Pour a single color batter into each cake pan. Place the remaining batter bowls in the fridge until ready to bake. (This helps to stop the baking powder from reacting while waiting to bake.)
  5. Bake for 20 minutes or until a toothpick inserted into the center comes out clean. Let the cakes cool for 10 minutes in the pan, then remove and finish cooling on a wire rack. Wash the pans, grease and line with parchment paper again, and bake the remaining batters.
For the Buttercream:
  1. In a large mixing bowl or the bowl of a stand mixer fitted with the whisk attachment, beat the butter and salt on medium speed until very fluffy and pale, about 5 minutes.
  2. With the mixer on low speed, gradually add the confectioners’ sugar a cup at a time, adding a tablespoon of cream at a time throughout mixing. Stop and scrape down the bowl occasionally during mixing. Once all of the sugar is added, beat in the vanilla and add additional cream if the frosting feels grainy when rubbed between your fingers. Increase the speed to medium-low and beat until light and fluffy, about 1 minute.
For the Assembly:
  1. Remove the parchment paper from the cake layers. Place the purple layer on a cake plate and spread ½ cup of frosting over the top. Place the blue layer on top and spread another ½ cup of frosting on top. Repeat with the remaining cake layers in the order of green, yellow, orange, and red. Spread the remaining frosting all over the outside of the cake. Chill the cake for at least 1 hour before serving. Leftover cake should be covered and can be stored at room temperature for up to 3 days.

Notes

  • Use a kitchen scale to measure flour for accuracy and avoid a dense cake.
  • Trim domed cake layers with a serrated knife for even stacking or use cake strips during baking.
  • Allow cake layers to cool completely before applying buttercream to prevent melting.
  • Keep butter at room temperature before creaming to ensure smooth frosting without lumps.
  • Chill the cake after frosting for better layer adherence and cleaner slicing.
  • Avoid over-mixing the batter to prevent a tough or dense texture.

Nutrition Information

Calories 1440kcal (72%) Carbohydrates 192g (64%) Protein 10g (20%) Fat 73g (112%) Saturated Fat 32g (160%) Polyunsaturated Fat 18g (106%) Monounsaturated Fat 18g (90%) Trans Fat 2g (100%) Cholesterol 198mg (66%) Sodium 497mg (21%) Potassium 158mg (3%) Fiber 1g (4%) Sugar 150g (300%) Vitamin A 1496IU (30%) Vitamin C 0.1mg (0%) Calcium 136mg (14%) Iron 3mg (17%)

Nutrition Facts

Serving: 12 servings

Amount Per Serving

Calories 1440

% Daily Value*

Calories 1440kcal 72%
Carbohydrates 192g 64%
Protein 10g 20%
Fat 73g 112%
Saturated Fat 32g 160%
Polyunsaturated Fat 18g 106%
Monounsaturated Fat 18g 90%
Trans Fat 2g 100%
Cholesterol 198mg 66%
Sodium 497mg 21%
Potassium 158mg 3%
Fiber 1g 4%
Sugar 150g 300%
Vitamin A 1496IU 30%
Vitamin C 0.1mg 0%
Calcium 136mg 14%
Iron 3mg 17%

* Percent Daily Values are based on a 2,000 calorie diet.