Crush the sandwich cookies in a food processor until finely ground.
Stir in melted butter until evenly combined, then press the mixture into a parchment-lined 9x13 inch pan. Freeze for 15 minutes.
Spread half of the vanilla ice cream over the crust and sprinkle 1 cup of peanuts on top. Freeze for 30 minutes.
Pour the hot fudge over the peanuts and smooth it out with a spatula. Freeze until set, about 30–45 minutes.
Spread the remaining ice cream on top and sprinkle with the remaining peanuts. Freeze overnight until fully firm.
Slice into bars, top with whipped cream if using, and serve immediately.