For the crust: Preheat the oven to 175°C. Crush the cookies until they're fine crumbs. Pour the melted butter over the top and stir with a fork to combine. Press into a pie pan and bake until set, 5 to 7 minutes. Remove from the oven and allow to cool completely.
For the filling: Beat the peanut butter with the cream cheese until smooth. Add the powdered sugar and beat until smooth. Add in the thawed whipped topping and beat until smooth, scraping the sides as needed.
Pour the filling into the crust, evening out the top with a knife or spatula. Chill for at least an hour before serving.
Warning: This is ultra, ultra-rich. Cut small slivers-your guests will thank you!