01 -
Preheat oven to 350°F. Grease and flour two 9-inch round cake pans to ensure easy release.
02 -
In a medium bowl, whisk together the all-purpose flour, baking powder, and salt until evenly combined.
03 -
In a large mixing bowl, beat the softened butter and granulated sugar with an electric mixer until light and fluffy in texture.
04 -
Add egg whites one at a time, beating thoroughly after each addition, then stir in the vanilla extract.
05 -
Alternately add the dry ingredients and the milk to the butter mixture, beginning and ending with the dry ingredients. Mix just until incorporated.
06 -
Divide the cake batter evenly into two bowls. Tint one portion with pink food coloring and the other with blue. Gently fold 1/2 cup chopped cotton candy into each portion.
07 -
Transfer both colored batters into the prepared cake pans. Swirl with a knife to create a marbled effect. Bake for 25 to 30 minutes or until a toothpick inserted in the center comes out clean.
08 -
Cool the cakes in the pans for 10 minutes, then turn out onto wire racks and allow to cool completely before frosting.
09 -
In a bowl, beat the softened butter until creamy. Gradually add the powdered sugar and vanilla, then add the milk as needed until smooth and spreadable. Divide frosting in half and tint one portion pink and the other blue.
10 -
Frost the cooled cakes alternately with pink and blue buttercream. Just before serving, garnish the cake with additional cotton candy.