Does anyone know how to take a white cake mix and make it chocolate? I have a very small marble cake to do, and I don't want to have to make 2 cake mixes. I have read somewhere to just add unsweetened cocoa powder? Any other suggestions? Thanks!!!

If you add more dry ingredient, you should probably add add'l liquid to offset it or the cake will be too dry .. or the batter too thick to bake properly.

I have a cookie recipe that I make vanilla and chocolate. The chocolate version's flour/cocoa quantity is the same as the vanilla's flour-only quantity. (16 cups of flour for the vanilla ..... 13 cups flour + 3 cups cocoa for the chocolate version).

Hmmm.... I am only making a 6" cake, so I don't need that much batter... but you are right about adding liquid to match the dry ingredients.

If you're doing that small an ammount, you might not need to add the liquid. If the chocolate is a little denser from the cocoa powder, it'll be less inclined to mix into an indistinct mass in the oven. You could also try adding melted chocolate--I'd go with a bittersweet or semi-sweet, or it'll be TOO sweet--because that would have a certain ammount of liquid in it just from the melted fats.

Melted chocolate ... great idea!!

Great thanks!
And that is what I was going to do, but I didn't have any chocolate in the house, just cocoa powder. I only made about 1/2 the batter chocolate and I added 2 TBSP of Cocoa powder, 1 TBSP of milk, and a heaping TBSP of Hot fudge ice cream topping. I thought it turned out good! I had enough extra to make 3 cupcakes, so me and DH got to try them.

Thanks for all the suggestions!