Found this cooking beauty in a blog the other day... isn't it like the cutest thing on earth? I didn't have to do too much research until I found the recipe, but anyway, it's basicly about making the classic flour-eggs-sugar-butter-milk cake, dividing the mixture into parts, adding different food colouring to each one and baking them separately. Then you make some frosting out of milk, butter and confectioner's sugar, and you use it between the layers and to cover it all.
You can find the recipe I took here: http://www.kludgymom.com/super-epic-rainbow-cake/ Think I'm gonna make it formy birthday the 29th this month. I know, looks like I was turning four instead of eighteen but... how the hellam I supposed to avoid craving for one like this!?