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Rainbow Birthday Cake

Rainbow Birthday Cake Recipe

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Prep Time 45 minutes
Cook Time 40 minutes
Total Time 1 hour 25 minutes
Servings: 12 servings
Calories: 458
Ingredients Method Notes

Ingredients
  

  • 3 cups all purpose flour
  • 1 tbsp baking powder
  • 1/2 tsp salt
  • 1 cup unsalted butter, room temperature
  • 2 cups granulated sugar
  • 4 large eggs, room temperature
  • 2 tsp vanilla extract
  • 1 cup buttermilk, room temperature
  • Gel food coloring in red, orange, yellow, green, blue, and purple
  • 1 1/2 cups unsalted butter, room temperature
  • 6 cups powdered sugar
  • 1/4 cup whole milk
  • 2 tsp vanilla extract
  • Rainbow sprinkles for decorating

Method
 

  1. Heat oven to 350°F (180°C). Grease six 6 inch round cake pans and line with parchment. Cream the 1 cup butter and sugar on medium until pale and fluffy. Beat in eggs one at a time, then the vanilla.
  2. Whisk flour, baking powder, and salt. Add to the butter mixture in three parts, alternating with buttermilk. Mix until just combined.
  3. Divide batter evenly into six bowls. Tint each with a separate gel color, stirring gently.
  4. Scrape each color into a pan. Bake 18 to 22 minutes for 6 inch pans. Cool in pans 10 minutes, then turn out onto a rack to cool completely.
  5. For the buttercream, beat 1 1/2 cups butter, powdered sugar, milk, and vanilla until smooth and fluffy.
  6. Stack the cooled layers with buttercream in between. Apply a thin crumb coat, chill 20 minutes, then frost the outside. Decorate with sprinkles and serve.

Notes

If you have only two pans, bake the layers in three batches and keep the remaining bowls of batter covered at room temperature. The layers can be made a day ahead, just wrap and refrigerate overnight.