Combine the chocolate cookie crumbs and melted butter in a bowl. Press the mixture firmly into the bottom and up the sides of a 9-inch pie plate. Chill the crust for 15 minutes.
In a large bowl, beat the softened cream cheese until smooth. Gradually beat in the powdered sugar until fully combined.
Mix in the vanilla extract, cold milk, crème de menthe liqueur (or mint extract), and peppermint extract, if using. Beat until the mixture is smooth.
Gently fold in the thawed whipped topping until no streaks remain. Fold in the mini chocolate chips.
Pour the mint filling into the chilled crust. Spread evenly.
Cover the pie loosely with plastic wrap and refrigerate for at least 6 hours, or preferably overnight, until the filling is firm.
Before serving, top with additional whipped cream and chocolate shavings.
Notes
For a non-alcoholic version, substitute the crème de menthe liqueur with 1/2 cup of milk mixed with 1 teaspoon of peppermint extract and green food coloring, if desired.
You can freeze this pie for a firmer, frozen dessert texture. Thaw slightly before slicing.
Use store-bought chocolate wafer crumbs to save preparation time.