I am making a 12x18 1/2 sheet cake. 2 layers high. I am trying to figure out how to do a mabled white and choc. cake. I think I know how to marble it. I am just wondering what the best way is so I don't waste a ton of cake. I will need 3 boxed cake mixes for each cake layer. So can I use 2 white cakes and 1 choc? I thouht you had to do white, choc,white choc and so on in each layer. Then swirl it in slightly. So I am not sure what to do. If I don't use a full box of mix can you store it for the next cake and if so how? I hope my question makes sense. Thanks! Oh yah one more thing the betty crocker cake mixes white and choc. bake for a different length of time. Will that affect it when baking them together?

From what I saw the other night on a challenge they just dumped in one flavor and then randomly spooned the other over the top and swirled it. And no it shouldn't affect the time, just bake until it's done. You might want to lower the temp by 25 degrees and cook longer though.

I have made quite a few marbled cakes. I do them in yellow/choc. I pour yellow mix first then spoon choc. batter here & there all over yellow batter, then just use a spatula or knife to make small swirls. I don't over swirl so it doesn't turn into light brown. Bake @ 325 for time on yellow box.

If you're using box mixes, I believe it's Betty Crocker makes a yellow/chocolate box mix.

I always just make the white cake, and pour about 3/4 of it into the pans. Add cocoa powder to the remaining batter, and a little more milk if necessary. Then pour the remaining "chocolate" batter into the pans and swirl through with a spatula.

Mandm78 - I do the same thing. It works great every time. Just spoon on the chocolate and then run a knife through the cake. I make rows with my knife up and down the cake. Sometimes I go the other way across the cake, too, but you can't do it too much or like Mandm78 said, it will all turn light brown and you lose the effect.

marbled seems to be the only cake i make these days as i offer to marble any of my flavours complimentary so that is what i alwasy end up doing!! all i do is make a half qnty for the size tin i am using of one flavour, poor that in then make the other half qnty for that sizzed tin poor that over the top then get my big soup ladle and gently fold the two together pulling the flavour up from the bottom and emptying on top once it all looks mixed around (obviously not to much or you may end up combining the two) i pop it in the oven, this method ensures that every piece has a bit of each flavour, other methods i have tried either don't get a good mis meaning that you end up with some pieces all one flavour and other methods mix it in to much. this i find marbles enough that in every piece you can see the clear contrast in flavour and colour in several sections.