Spray a 9×13 pan with cooking spray.
Bake nrownies as directed on box and let to fully cool.
Spread marshmallow cream.
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.
