Spray a 9×13 pan with cooking spray.
Bake Brownies as directed on box and let to fully cool.
Spread Jet-Puffed Mallow Crème.
Place Chocolate chips and peanut butter in a medium-sized microwave bowl and microwave until well blended stopping at 1-minute intervals.
Once melted stir in Rice Krispies and spread evenly over mallow crème.
Cover and chill for two hours before cutting into squares
Yields 24-36 bars depending on how big you like your squares