Sugar and corn syrup should be combined in a large saucepan. Bring to a boil over medium heat and stir in the sugar until it dissolves. (Corn syrup mixture can harden if boiled for too long.) Put away from the heat.
Combine the Rice Krispie cereal and peanut butter mixture in a large bowl and stir until evenly combined. Pack the cereal mixture into a 9x13-inch pan lined with parchment paper or butter.
Combine the butterscotch chips and chocolate chips by melting them together in a microwave-safe bowl or a saucepan over low heat. They're delicious on their own, but you can make a thicker topping if you like.
Layer the chocolate sauce on top of the Rice Krispies. Cool. Store in an airtight container after cutting into bars.
