Preheat oven to 350. Grease a 13x9x2 pan
Melt 2 sticks butter with 3/4 cup cocoa in the microwave, about 2 minutes. Add 2 cups of sugar, stir well – I use a whisk. Add 4 eggs, stir some more. Add 1 tbsp of vanilla, stir some more. Add 1 1/4 cup of flour and 1 tsp. Baking powder (Or self rising flour) and stir some more.
Switch to a spatula and mix on about a cup of chocolate chips. And nuts of you like. Turn into the pan.
Bake for about 30 minutes.
For peanut butter swirls, drop teaspoons of peanut butter around on the top and swirl with a knife before baking.