The best thing about this recipe is that there's so much room for experimenting (which is one of my favorite things in baking). If you have a die-hard chocolate fan, you can use a chocolate cake batter and a chocolate cookie batter, for 3 times more chocolate. For my first time baking this, I used a boxed brownie batter to make it a little simpler. Here's my favorite cookie batter (personalize it by adding your favorite mix-in, be it chocolate chips, M&M's or anything else!)
Hope you enjoy!