Oreo and Peanut Butter Brownie Cakes 1 box brownie mix, 8x8 inch size 24 Oreo Cookies 1/2 cup creamy peanut butter Preheat oven to 350 degrees and line a 12 muffin cup baker with paper liners. Prepare brownie mix according to package directions. For each cupcake cup spread 1 teaspoon of peanut butter over 2 Oreo cookies and stack them on top of each other. Spoon 2 tablespoons of brownie batter. Bake 18-20 min.