Line a 9 x 13-inch baking dish with parchment paper. Set aside.
To a large mixing bowl, add crispy rice cereal. Set aside.
To a medium saucepan over low heat, add corn syrup and sugar. Whisk continuously to create a grainy paste.
Once paste is formed, increase the burner heat and allow the mixture to come to a boil, then immediately remove from the heat.
Stir in peanut butter. Pour mixture into the bowl with cereal. Using a heat-proof spatula/spoon, stir to combine.
Grease your hands with butter or non-stick cooking spray. Using your greased hands, press the scotcharoos mixture into the prepared baking dish.
To a microwaveable bowl, add the chocolate and butterscotch chips. Microwave on High power in 30-second intervals, stirring between each, until mixture is smooth.
Pour over the top of the cereal bars and use an offset spatula to spread into an even layer.
Refrigerate for 1 hour. Remove from the refrigerator and allow the scotcheroos to come to room temperature for easier cutting.
Notes
Do not over cook the sugar mixture or the resulting treats will be tough.