To make cookie crust:
Heat the oven to 350F/180C and arrange a rack in the middle. Lightly grease a pie plate.
Place chocolate cookies in the bowl of a food processor fitted with a blade attachment and process until the pieces are about the size of peas. Stop the motor, add melted butter, and continue to process until the crumbs are fine, about the size of coarsely ground coffee.
Pour crumb mixture into a pie plate and your fingers, press firmly and evenly into the bottom and up the sides. about 10 to 15 minutes. Cool completely before filling.