Combine corn syrup, peanut butter, and sugar in a medium saucepan. Heat on medium heat, stirring, until melted and smooth. You do NOT need to bring the mixture to a simmer. It just needs to be warm, smooth, and easily pourable.
Add chopped pretzels and stir to coat evenly.
Scoop tablespoon-sized clusters onto parchment paper or wax paper-lined baking sheets.
Allow clusters to cool.
Melt chocolate chips and butterscotch chips in a double boiler or microwave. I usually use my microwave and heat the chocolate chips and butterscotch chips for 30 seconds, then I stir and heat them for an additional 15-20 seconds. Every microwave is different, my advice is to go low and slow. Short intervals, stirring until smooth and creamy. DO NOT OVERHEAT CHOCOLATE.
Spoon the chocolate mixture over the clusters.Refrigerate clusters until the chocolate hardens. Rotate clusters so that the bottoms are exposed to the air. This will allow them to dry and not be sticky.
Continue to allow clusters to dry for at least an hour.
Video
Notes
Storage: When the clusters are no longer sticky to the touch, they can be stored in the refrigerator or at room temperature in an airtight container, with parchment or wax paper separating the layers of treats.