Prepare a 13"x9" pan by lightly spraying nonstick spray. Melt sugar with corn syrup in a saucepan over medium-low heat. Once melted, add peanut butter and blend well. Remove from heat.
In a large bowl, add Rice Krispies cereal and pour corn syrup mixture into the cereal as you mix. Pour cereal mixture into the 13"x9" pan and spread evenly.
Melt milk chocolate chips and butterscotch chips in a small dish in the microwave. Stir every 30 seconds until melted through. Pour over top of the cereal and spread evenly. Allow to fully cool and let the top set until it is no longer gooey to the touch, about 2 hours, before cutting.