Rainbow Cake

This rainbow cake is what my oldest daughter wanted me to make for her birthday. She saw this cake on my pinterest page about 8 months before her birthday and knew this was the cake she wanted. She loved that it had all of the colors of the rainbow.

I love how it looked frosted in all white, because once you cut into the cake it made the colors stand out that much more. This is a very sweet, but good cake.

Rainbow Cake

Ingredients:

White Cake

• 2 sticks unsalted butter, room temperature
• 2 1/3 cups granulated sugar
• 5 egg whites, room temperature
• 2 teaspoons vanilla extract
• 3 cups all purpose flour
• 4 teaspoons baking powder
• 1/2 teaspoon salt
• 1 1/2 cups milk
• red, orange, yellow, green, blue, and purple gel food coloring

Swiss Meringue Buttercream

Filling and Crumb Coat

• 9 egg whites
• 1 3/4 cups granulated sugar
• 4 sticks unsalted butter, room temperature
• 2 teaspoons vanilla extract

Frosting

• 5 egg whites
• 1 cup granulated sugar
• 2 sticks unsalted butter, room temperature
• 1 teaspoon vanilla extract

Directions:

White Cake

1. Using as many 9-inch cake pans as you have (it doesn't matter how many you have you can just reuse them), grease the sides and line the bottom with parchment paper.
2. Preheat oven to 350°F.
3. In a large bowl sift the flour, baking powder, salt and give it a quick stir. Set aside.
4. In another large bowl cream the sugar and butter.
5. Add in one egg white at a time, then add the vanilla and mix until fully incorporated.
6. Mix in half of the milk and then half of dry ingredients, followed by the rest of the milk and the rest of the dry ingredients.
7. Divide the batter evenly among 6 bowls (it is about 1 cup each) and mix in the various gel food coloring until you achieve the color desired.
8. Pour the batter into the prepared pans and bake for 15 minutes or until an inserted toothpick comes out clean.
9. When the cakes are done remove from oven and place on a cooling rack in pan for 10 minutes.
10. Remove the cakes from the pan and cool completely (for a quicker cool, cover and place in the fridge).

Swiss Meringue Buttercream

1. Cook the egg whites and sugar in a small saucepan over medium heat, whisking constantly, until the sugar is completely dissolved and the mixture reaches 160 degrees on a thermometer. Test to make sure the sugar is dissolved by rubbing a small amount between your fingers. If it is completely smooth, it is done. If it feels gritty continue cooking and whisking (will take about 5 minutes).
2. Pour the mixture into the bowl of a stand mixer and using a whisk attachment, whip on high speed until room temperature and the mixture creates stiff peaks and is nice and glossy (will take about 10 to 15 minutes).
3. Turn the mixer down to medium-high speed, add butter 1 tablespoon at a time, making sure it is completely incorporated before adding more butter.
4. After adding all of the butter turn the mixer back to high speed until the mixture comes together (will take about 5 minutes). If the mixture does not come together at this point put it in the fridge for 5 to 7 minutes and then whip again on high until mixture comes together.
5. Add in the vanilla extract and beat just to incorporate.

Cake Assembly

1. Put the purple cake layer down on a serving platter and frost the top of it using the filling and crumb coat buttercream. Continue stacking and frosting the rest of the cake layers, in reverse rainbow order. Once you add the last cake layer, red, crumb coat the entire cake (lightly frost to seal in crumbs) and put into fridge for a little bit to set.
2. Using the frosting buttercream frost the entire cake, saving some frosting if you want to add some decorative details.
3. This cake can be stored at room temperature with no problems or you can put it in the fridge. If you store it in the fridge, the frosting may harden a bit, but leaving it out until room temperature will soften the frosting again.

Enjoy!!!

Adapted from Whisk Kid.