Line a 9x13-inch or 7x11-inch pan with aluminum foil. Spray lightly with cooking spray.
Place corn syrup and both sugars in a large saucepan. Heat over medium-low, stirring until mixture comes to a boil. Turn heat off. Stir in peanut butter and salt until smooth.
Quickly stir in Rice Krispies. Transfer mixture to prepared pan, spreading it out evenly.
Make chocolate topping. Place chocolate chips, butterscotch chips, and 2 tablespoons peanut butter in a small saucepan. Heat over medium-low, stirring constantly, until smooth. Pour on top of rice krispies mixture.
Sprinkle chopped peanut butter cups on top. Wait for chocolate topping to set before slicing into squares. You can place it in the refrigerator to speed this up.