"Rainbow Cupcake Frosting" Could be done on rainbow cupcakes. This looks yummy as well as pretty. I'm not a big fan of sweets, and I have little to no fondness for chocolate cupcakes, but I totally want to eat that.
Dark Chocolate Raspberry Curd-filled Cupcakes -- For curd - use fresh raspberries, and less butter or liquid for more solid curd. Cupcake batter - try sugar and flour. Frosting - use two vanilla beans to steep.