Marbling a cake requires two things: cake mixes and the ability to know when to stop.
Yes, I'm using store bought cake mixes. I never said they were the devil; but, apparently I've left that impression on people. My mother in law, in fact, apologizes to me every time she uses one. I can't get her to stop doing that. ....And am I really that intimidating? The rule of thumb on all things in this house is one of common sense. If it works for you, that's your thing.
|trim the parchment to fit|
Mix you white or yellow cake mix as directed on the box, then scrap into a waiting bowl. Now mix your chocolate batter.
Each cake mix produces 4-6 cups of batter. A standard 9x13 sheetcake needs 7 cups of batter for a 2 inch tall cake (like you would buy at the grocery store...only if things are spelled wrong, it's your fault).
Add four cups of yellow or white batter to the pan and spread out with a offset spatula, making sure to add a little extra batter to the corners. (Corners are notorious for being the shortest part of a sheet).
Next, add in three cups of the chocolate batter to the center. (* the amount of batter than you use varies by pan size but you should use 1 cup more of the white or yellow batter than the chocolate if an odd number of batter is called for).
Using the offset spatula or a butter knife, begin swirling the batters together, pulling the light into the dark and the dark to the edges. Be sure to have the tip of your knife all the way to the bottom of the pan for even mixing.
Now, STOP. There comes a point when you have mixed too much and the dark will absorb the light batter and you won't have a marble cake anymore but a large chocolate cake, so whoa, Bessy.
Bake cake according to directions on box for smaller cakes. For larger cake, you may need to drop the temp of the oven to 325.
When the cake is spongey in the center and the edge have pulled away from the sides of the pan, remove it from the oven to cool on a rack. After 10 minutes, flip the cake out of the pan so steam can escape from the pan and cake.