Combine white Karo syrup and granulated sugar in a saucepan.

Heat the mixture over medium heat until it almost reaches a boiling point.

Remove from heat and stir in the peanut butter until smooth.

Add Rice Krispies to the peanut butter mixture and stir until well combined.

Press the Rice Krispies mixture into the bottom and up the sides of a 9 or 10-inch pie plate to form the crust.

Allow the crust to cool completely.

Slightly soften the chocolate marshmallow ice cream (or your preferred flavor).

Fill the cooled pie crust with the softened ice cream.

Spread Cool Whip evenly over the ice cream.

Sprinkle chopped nuts on top of the Cool Whip.

Place the pie in the freezer until it is firm, about 30 minutes.

Before cutting, let the pie sit at room temperature for a few minutes or dip the bottom of the pie plate in warm water for a few seconds to loosen.

Cut into slices and serve immediately.