Bake brownies as directed on box. Set aside and let cool.
Mix vanilla pudding mixes with 2 cups of milk. Add vanilla extract and peanut butter. Fold in cool whip.
In the bottom of trifle bowl, break apart chunks of brownies. Add a layer of Reese cups (I leave mine whole). Pour pudding mixture on top of Reese cups. Repeat steps until all ingredients are gone, you should end up with pudding mixture on top. Garnish top with Reese cups or however you would like :)