Preheat oven to 350F.

Grease a 9″ x 11″ casserole dish and set aside.

In a large bowl, beat together the white cake mix and cotton candy soda for 2 minutes. Adjust the color with light blue food dye, if desired. (If using, make the cake batter a deeper blue than you want the finished cake to be as it will lighten with baking.)

Bake for 25-30 minutes, until an inserted toothpick comes out clean.

Allow the cake to cool completely before frosting.

Meanwhile, place 1 cup of cotton candy soda in a saucepan and heat until boiling over medium-high heat. Reduce to medium-low and simmer until reduce to 1/4 (2 oz of soda should remain). Allow to cool completely.

In a large bowl, beat together the butter and powdered icing sugar for 2 minutes, then add the reduced cotton candy soda. Beat to incorporate, then add the milk as needed to achieve a spreadable texture. Adjust the color with blue food dye, if desired.

Use an offset spatula to spread the frosting on the cooled cake.

To achieve the fun texture shown in the pictures, use short strokes to spread the frosting, then go back over the frosted cake and rough it up a bit.

Garnish the cake with sprinkles, as desired.