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 Sunkist for 2 minutes.

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 Sunkist 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 Sunkist soda. Beat to incorporate, then add the milk as needed to achieve a spreadable texture. Adjust the color with orange 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 and orange slices, as desired.