Prepare a cake mix, or your favorite recipe for cake. Crumble some of it and mix it with 1/2 can or 1/2 recipe of your favorite frosting (heating the frosting to make it very soft is recommended). Press this into the bottom of a pie pan and fill it halfway up. Take vanilla, chocolate, or strawberry ice cream and let it soften (not melt) in the fridge for 1/2 hour.
Swirl the ice cream over the cake in the pie pan, so it looks like swirls of frosting. Put sprinkles on the top and serve. This can be made ahead and frozen, but let thaw before serving.