I need to make a Wedding chocolate cake and I only have a regular vanilla cake recipe that I always make because is good for tiers and I add syrop and stay sturdy.

My question is if can I add hersheys cocoa powder to this recipe and how do I know the amount? (the bride want me to use it because its dark choc.)
I search for all kind of recipes but I need one with self rising flour and butter and I could find any similar to mine.