This is just a simple variation on marble cake - you can make it from scratch or from a box. Take two glass measuring cups and divide the batter - one chocolate and one white. In a prepared round pan, pour a small amount of one batter in the middle and quickly pour a small amount of the other in the middle - on top of the other one alternately - work quickly and evenly with the batter. Bake as directed and wait for the suprise when you cut into it.