In a medium bowl, stir together the graham cracker crumbs, melted butter, and sugar. Press firmly into the bottom and up the sides of a 9-inch pie plate. Refrigerate while preparing the filling.

In a large bowl, whisk together the instant chocolate pudding mix and cold milk for about 2 minutes, until it begins to thicken.

Stir in the vanilla extract.

Fold in the 8-ounce container of Cool Whip until the filling is smooth and fluffy.

Spoon the filling into the prepared crust and smooth the top.

Spread the remaining Cool Whip evenly over the pie.

Sprinkle with the chopped peanut butter cups.

Microwave the peanut butter for about 15 to 20 seconds, just until smooth enough to drizzle. Drizzle it over the top of the pie.

Refrigerate for at least 4 hours before serving.