They're a little more time consuming than regular cupcakes because you have to mix and pour in all the individual colors, but the end result is well worth it!
* Box of white cake mix and necessary ingredients to make the cake (mine called for egg whites, oil and water)
* Food coloring
1. Preheat your oven to 350 and put paper liners in your cupcake pan. I followed the directions for adding the food coloring to the batter given HERE. However, instead of doing it in bowls, I put the cake batter into ziploc bags, added the drops of food coloring, sealed and then squished the bags to mix the colors. (Note: You'll need about 2/3 - 3/4 cup of batter in each bag)
The colored batter is in the bags. Just clip a corner to squeeze it into the wrappers.
2. Then, all I had to do was clip a corner of the bag and I could squeeze the batter into the cupcake liners. I found that I could only make 15 cupcakes, but I think I put a little too much batter into my first ones. Also, I found that squeezing the batter right up against the cupcake liner (instead of just in the center) helped make sure that you could see all the colors of the rainbow when you pulled the wrapper off.
3. Bake according to the box instructions. Let the cupcakes cool. To serve, peel off the cupcake liner and top with a dollop of whipped cream.