Birthday Rainbow Cake

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This birthday rainbow cake is a moist vanilla cake dyed to look like a rainbow. It has a cream cheese frosting with tons of sprinkles and a pink drip.

Prep Time1 30

Cook Time18

Total Time1 48

Servings: slices

Calories: 796kcal

Author: Stephanie Rutherford

Ingredients

Vanilla Cake

3 ¼ cup All-purpose flour
1 tablespoon Baking powder
1 teaspoon Salt
1 cup Unsalted butter room temperature
1 ¾ cup White granulated sugar
½ cup Sour cream room temperature
4 Egg whites room temperature
2 Large eggs room temperature
1 tablespoon Clear vanilla extract
1 ⅛ cup Buttermilk room temperature

Cream Cheese Frosting

1 ½ cups Unsalted butter slightly cold
8 oz Cream cheese room temperature
9 ½ cups Powdered sugar sifted
3 teaspoon Pure vanilla extract
¼ cup Heavy Cream *This is enough frosting to only frost the cake.

White Chocolate Drip

1 cup White chocolate chips use a quality brand
⅓-1/2 cup Heavy cream

Instructions

Vanilla Cake

Preheat the oven to 350°F. This cake makes 6 layers in 6 inch cake pans. Spray cake pans with baking non-stick spray. Place a parchment circle on the bottom of the pan and spray again.
In a mixing bowl, sift the flour, baking powder, and salt. Using a mixer, beat the butter and sugar together. Beat on medium-high for 3 minutes. Beat until light and fluffy. Add in sour cream and vanilla. Scrape the bowl. Mix until combined.
Add in eggs and egg whites one a time on medium-low. Scrape the bowl halfway through.
Add in ⅓ of the dry ingredients and half of the buttermilk. Mix until slightly combined on low. Add in another ⅓ of the dry ingredients and the rest of the buttermilk. Mix. Add in the rest of the dry ingredients. Scrape the bowl and mix for 15 seconds.
Separate the batter evenly in 6 bowls. Color each batter a separate color of the rainbow. Mix gently. Pour each color into pans.
Bake for 18-20 minutes. The cakes are done baking when a toothpick inserted comes out clean. Let the cakes sit in the pans for 10 minutes before transferring to a cooling rack. Allow the cakes to cool completely.

Cream Cheese Frosting

Set the butter on the counter for 30 minutes to get slightly cold. While waiting, sift the powdered sugar.
Beat the room temperature cream cheese on high for 1 minute. Add in butter and beat for 1-2 minutes until the butter is mixed in with no butter chunks remaining. Slowly add in powdered sugar.
Add in heavy cream and vanilla. Mix on low until just combined. Switch to high and beat for 1-2 minutes until it becomes slightly lighter in texture. Chill for 15 minutes before decorating cake.

White Chocolate Drip

Pour white chocolate chips in a bowl and set aside. Heat heavy cream in a saucepan over medium-low heat. Heat until hot and steaming. Pour ⅓ of the cream over white chocolate chips and let it sit for 1 minute and 30 seconds. Mix until smooth. The consistency should be smooth and pourable down the sides of the cake. Add a little bit of the leftover hot cream into the ganache. Mix until smooth. I didn't use all of the leftover cream.
Optional* add a tiny amount of pink food dye.

Assembly

Place first layer of cake bottom side down. Frost the inside with frosting. Repeat with 2nd-5th layers. Place last layer bottom side up.
Apply a light layer of frosting over the cake. This will act as the crumb coat layer. Freeze for 15 minutes. Then, frost the rest of the cake.
Apply rainbow sprinkles on the bottom of the cake for a waterfall look. Pour the white chocolate ganache on top of the cake. Use an offset spatula to push the chocolate over the edges of the cake.

Notes

Flour- Make sure flour is spooned and leveled or use a kitchen scale. Compacted flour can dry out the cake.

High altitude baking- Add an extra 3 tablespoon of flour.

Pull out dairy ingredients 2 hours before baking

If you want enough frosting to top the cake with a border. Increase frosting to:

2 ¼ cup butter

12 oz cream cheese

13 ½ cups powdered sugar

1 tablespoon vanilla

¼ cup heavy cream plus 1 TBSP.

Nutrition