Prepare a 9x13-inch pan by spraying it with cooking spray.
In a large saucepan, combine granulated sugar with corn syrup. Place it over medium-high heat and cook until the sugar is fully dissolved, stirring continuously.
Remove from the heat, and stir in peanut butter. Gently fold in the Rice Krispies cereal. Transfer the mixture to the prepared pan and gently press it down with your hands into an even layer. Set aside.
Combine the semi-sweet chocolate chips and butterscotch chips in a medium heat-safe bowl. Microwave for 30 seconds, then stir. Repeat the process, microwaving at 30-second increments until all the chips have melted.
Pour the chocolate butterscotch mixture over the Rice Krispies mixture, and spread it evenly with a spatula.
Place the pan of scotcheroos in the refrigerator for 30 minutes, or until the chocolate has hardened. Cut into squares to serve.
Notes
Avoid overcooking the sugar. If you cook it too long, you will end up making something with a texture closer to hard candy! Keep a close eye on the pan, and remove it from the heat as soon as all of the sugar crystals have dissolved.
Try them with other cereal. Rice Chex or Crispix can be used in place of the crisped rice cereal if you prefer. Cornflakes work too!
Don't have butterscotch chips? That's ok! Use all chocolate chips, or a combination of chocolate chips and peanut butter chips to make the topping.
Substitute almond butter or another nut butter for the peanut butter if you'd like to.
To Store: Keep these in an airtight container for up to 4 days. You can store them at room temperature or in the fridge, just be sure to bring them to room temperature before serving.
To Freeze: Wrap individually with plastic wrap, then store in an airtight container or freezer bag for up to 2 months in the freezer.