Ingredients
for the Cake
1 3/4 cups all-purpose flour
1 1/2 teaspoons baking powder
3/4 teaspoons table salt
1 cup granulated sugar
1 1/2 sticks unsalted butter, softened but slightly cool, cut into 12 pieces
3 large eggs
3/4 cups milk
1 1/2 teaspoons vanilla extract
Times three (in other words, make the recipe above 3 times, thus 3x the ingredients)
for the frosting
1 cup (2 sticks) unsalted butter, at room temperature
16 oz (2 packages) cream cheese, at room temperature
2 teaspoons vanilla extract
1/2 teaspoon salt
8 cups confectioners sugar
You will also need: red, orange, yellow, green, blue and purple food gel and edible glitter
Directions
For the cakes: You will have to repeat this process three times, splitting the batch each time in half and adding a significant amount of each food gel color…
Preheat oven to 350F. Prepare 2 9-inch spring form pans with baking spray and set aside.
In the bowl of a stand mixer, combine the flour, baking powder, salt, and sugar on low speed. Add the butter, 1 piece at a time, and combine until the mixture resembles coarse sand. Add the eggs, 1 at time, and mix until fully combined. Add the milk and vanilla, increase the speed to medium, and mix until the batter is light, fluffy and free of lumps. Split the batter into two bowls and tint each with a color of food dye. Fill the batter into each spring form pan halfway. Bake until a toothpick inserted in the center of the cupcake comes out clean, about 31-35 minutes. Cool the cakes in the pan for 5 minutes, then transfer to a wire rack to cool completely.
Repeat until you have all the colors of the rainbow.
To make the frosting, cream together the butter, the cream cheese, salt and vanilla until light and fluffy. Mix in the confectioners sugar a little bit at a time. The frosting may be a little loose, so add a bit more powdered sugar as necessary. Refrigerate to set for 20-30 minutes.
To assemble: Place each layer of the rainbow cake, in order (purple, blue, green, yellow, orange and red) together, held together by a layer of frosting. Apply a crumb coat to the whole cake and let set for 30 minutes in the refrigerator. Then do a final coat of the frosting. Finally, apply glitter in whatever patter you like. Refrigerate until ready to serve.
