All I did was buy my favorite white cake mix. I made the mix as directed on the box (always using egg whites so the yellow eggs don't tint the white cake even slightly~not that I know it does..I've just never risked it!!!!). Then I split it into six different small bowls, as evenly as I could. Red, Orange, Yellow, Green, Blue, Purple (yep..a rainbow..ROY G. BIV ;) ) Then I put just a drop or two into each to color it. You really do NOT need a lot at all!!!! Remember..too much changes the taste and it's nasty!!!! You, of course, will need to do color blending for ones like purple and orange..but always start with the smallest amount of dye to color it!! When you've done that, drop a spoonful, or a half, into the cupcake tins. I always alternated which colors I did in what order so they weren't all the same rainbow. Bake them as directed on the box for cupcakes! Super easy!!!!!
I had white icing which I colored green then added mini marshmallows on top. It was like the grass and clouds type of thing for the rainbow! We had so many so we took some to friends of ours. We're told their little girls loved them!!! Yeah!!!!
Seriously~make these for your kids! They will love them and the surprise rainbow inside!!!!
Have a happy day~Kasey