Prepare brownie mix according to package directions or recipe. Preheat oven to temp called for on package/directions.
Line an 8x8 or 9x9 pan with foil and spray with non stick cooking spray.
Prepare peanut butter topping in a separate bowl by combining peanut butter, butter, powdered sugar and cereal. Set aside.
Spread a thin layer of brownie batter on the bottom of your pan, making sure to cover the entire bottom of the pan.
Place your jumbo Reese's Peanut Butter Bars on top of your thin layer of brownie batter.
Cover the bars with the remaining batter.
Drop the peanut butter mixture over the top of your brownie batter and use a knife to swirl into your brownie batter.
Bake according to package directions or brownie recipe. These brownies may require an additional 5 5 to 10 minutes baking time.
Remove from the oven and allow to cool.
Cut up and serve! Delicious served warm topped with ice cream!