Prepare the Pan: Lightly grease a 9×13-inch baking pan with the tablespoon of butter and set aside.

Make the Base: In a large saucepan over medium heat, combine the light corn syrup, sugar, and peanut butter. Stir constantly until the mixture melts together and becomes smooth.

Add Cereal: Remove the pan from heat. Add the crisp rice cereal and stir until the cereal is fully coated and evenly mixed.

Press Into Pan: Transfer the cereal mixture into the prepared pan. Use a spatula or buttered hands to press it down into an even layer.

Melt the Topping: In a microwave-safe bowl or over a double boiler, melt the semisweet chocolate chips and butterscotch chips together, stirring until smooth.

Top the Bars: Pour the melted chocolate–butterscotch mixture over the pressed cereal base. Spread evenly.

Set: Allow the bars to cool and the topping to firm up — about 20–30 minutes at room temperature (or chill to speed it up).

Slice and Serve: Once set, cut into squares and enjoy.