Preheat your oven to 350°F (175°C) and grease two 9-inch round cake pans, then flour them.

In a large mixing bowl, combine the white cake mix, eggs, milk, and vegetable oil. Mix on medium speed for about 2 minutes until smooth.

Split the batter into separate bowls and add food coloring to each bowl.

Pour the colored batters into the prepared pans, layering them alternatively. Bake for 25-30 minutes, or until a toothpick comes out clean.

Allow the cakes to cool for 10 minutes in the pans, then transfer to a wire rack to cool completely.

Spread a layer of buttercream frosting between the two layers, then cover the entire cake with frosting.

Top the cake with fluffy cotton candy, and decorate with sprinkles if desired.