Preheat your oven to 350°F (175°C) and line two standard muffin tins with a total of 18 paper cupcake liners; set aside. To prepare the cake batter, combine the white cake mix, egg whites, vegetable oil, water, and cotton candy flavoring in a large bowl. Using an electric mixer, beat the mixture on medium speed for about 2 minutes until smooth and well-blended. Divide the batter evenly into two bowls. Tint one bowl with pink food coloring and the other with blue—just one drop of each color is enough to achieve a soft pastel hue.

Distribute the colored batters evenly into the prepared cupcake liners, layering them without swirling so the colors remain distinct. Fill each liner about three-quarters full. Avoid swirling the batters together, as it can result in muddy or dull tones instead of clean pastel layers. Bake for 15 to 18 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs. Let the cupcakes cool completely on a wire rack before frosting.

To make the frosting, place the softened butter, cotton candy flavoring, and vanilla extract into the bowl of a stand mixer. Beat on medium speed until smooth and creamy, about 1 minute. Gradually add the confectioners’ sugar one cup at a time, alternating with small additions of heavy cream or milk. Beat until the frosting is light, fluffy, and spreadable. Divide the finished frosting into two separate bowls and tint one with blue food coloring and the other with pink. Again, one drop of each coloring is sufficient for a pastel effect.

Prepare a large piping bag fitted with your favorite piping tip. Spoon the pink frosting down one side of the piping bag and the blue frosting down the other side. Don’t worry if the colors mix slightly at the tip—it will create a soft purple swirl that enhances the cotton candy theme.

Pipe the two-toned frosting generously onto the cooled cupcakes, creating a beautiful swirl on each. Sprinkle the tops with blue and pink sanding sugar for extra sparkle and color. To make the cotton candy toppers, tear off small pieces of cotton candy and attach them to the moistened ends of popsicle sticks—just dip the tip of each stick in water so the cotton candy adheres easily. Add the cotton candy sticks to each cupcake just before serving, as cotton candy reacts quickly to air and can harden or shrink. For best results, prepare and place the cotton candy toppers right before presenting your cupcakes.