Place cereal in a large heat-proof bowl; set aside. In a small saucepan, combine the peanut butter, corn syrup and sugar. Cook over medium heat until sugar is dissolved, stirring occasionally. Pour over cereal; toss to coat.
Spread into a greased 13-in. x 9-in. pan. In a microwave, melt chocolate and butterscotch chips; stir until smooth. Spread over bars.