Cook sugar, peanut butter and Karo syrup in a saucepan over medium heat until smooth and mixture starts to bubble, about 5 minutes. Add Rice Krispies and mix together. Remove from heat and press Rice Krispies mixture into a 9" x 13" greased pan.
In a small glass bowl, melt butterscotch and semi-sweet chocolate chips in the microwave until smooth (can use a double broiler instead). Spread mixture evenly over Rice Krispies. Let scotcheroos sit for a few hours, so chocolate topping hardens.
Recipe by sweet caroline's cooking at https://sweetcarolinescooking.com/2012/12/30/sweet-start-to-the-new-year-scotcheroos/