How to change a vanilla cake recipe to make a chocolate cake?
I did this as an experiment last month, because I wanted a marble cake. The part that I wanted chocolate, I just swapped out a half-cup of the flour for cocoa. I should note, however, that while it tasted great, it made a denser, slightly drier cake than did the white cake batter. Next time, I plan to add a couple of teaspoons of grapeseed oil and some extra baking powder to counteract that problem.