Place hot fudge sauce in a microwave safe bowl and microwave on high until hot, 1-2 minutes. Do not let the fudge boil. Stir peanut butter into hot fudge until smooth. Let cool to room temperature.

Line the bottom of a 9x13 inch baking dish with ice cream sandwiches, trimming sandwiches to fit, as needed.

Spread half of whipped topping over sandwiches. Place dessert in freezer for about 15 minutes, or until whipped topping is firm. Remove from freezer and spread half of fudge mixture over the whipped topping. Sprinkle with half of the peanuts.

Repeat the layers, ending with hot fudge and peanuts. Freeze until firm, about 2 hours. Cut into squares to serve. Drizzle with additional hot fudge sauce, if desired.