Lightly grease a 9×13-inch baking pan or line it with parchment paper, leaving extra hanging over the sides for easy removal later. Place the rice cereal in a large mixing bowl and set it aside.

Add the sugar and corn syrup to a medium saucepan and warm the mixture over medium heat, stirring occasionally, until the sugar has dissolved and the mixture looks smooth and glossy. Do not allow it to boil. Remove the pan from the heat and stir in the peanut butter until fully combined and smooth.

Pour the warm peanut butter mixture over the cereal and gently fold everything together until the cereal is evenly coated. Transfer the mixture to the prepared pan and press it into an even layer using light pressure to avoid packing it too tightly.

Combine the chocolate chips and butterscotch chips in a microwave-safe bowl and heat in short intervals, stirring between each, until melted and smooth. Spread the melted topping evenly over the cereal layer.

Let the bars sit at room temperature until the topping has set, or refrigerate briefly to speed up the process. Once firm, lift the bars from the pan and slice into squares before serving.