Preheat oven to 350°F
Mix together dry ingredients - cocoa, flour, baking powder and salt. Set aside.
Mix sugar and melted butter. Add eggs and mix.
Slowly add dry ingredients while mixing.
Stir in chocolate chunks.
Line an 8x8 baking dish with foil. Press foil down firmly into the dish. Spray with non-stick.
Pour batter into prepared dish and spread evenly. (batter will be thick)
Microwave peanut butter 30 seconds. Drizzle melted peanut butter on top of brownies. Swirl into batter using a knife.
Bake at 350° for 40 minutes or until almost cooked through. (brownies will continue to cook after being removed from oven)
Once cooled, remove the foil and brownies from baking dish. Carefully peel foil away from brownies and slice into 12 pieces.