Coat a 9x13 baking dish with cooking spray, set aside.
In a medium saucepan, stir together light corn syrup and sugar, cooking until sugar dissolves and starts to boil.
Remove from heat, stirring in peanut butter and vanilla until smooth.
Fold in Rice Krispie cereal until entirely coated. Press into prepared pan.
Melt chocolate chips, butterscotch chips and butter in a double boiler until shiny and just melted. See notes for the best ways to melt chocolate above.
Pour over Rice Krispie mixture, spreading evenly, and place into the refrigerator to set.
Remove after chocolate topping has hardened. Cut into squares. Serve and store at room temperature.