Spray a 9x13" pan with cooking spray and set aside. In a large microwave safe bowl, add the marshmallows, peanut butter and butter. Microwave on high, watching and stirring every 30 seconds until it is all incorporated and smooth. Add the rice krispies and stir carefully to coat. Transfer mixture to the prepared pan and flatten out with a spatula sprayed with cooking spray.

Melt the chocolate and butterscotch chips in a small microwave bowl on 30 second intervals, stirring and until smooth. Pour over the rice crispies and spread with a spatula. Let cool and cut into 24 squares.