16Reese's peanut butter cups, coarsely chopped (full size, not miniature)
In a large bowl combined the cookie crumbs and melted butter, mix well. Press evenly into the bottom and sides of a lightly buttered 9-inch springform pan. Put in the freezer for 30 minutes.
While the pie crust is chilling, remove the ice cream from the freezer and let it soften at room temperature (don't let it thaw completely).
In a large bowl combine the softened ice cream and Cool Whip. Stir until smooth and well combined. Fold in half the chopped peanut butter cups.
Pour into the chilled crust and spread evenly.
Place the peanut butter in a microwave-safe bowl and heat for 30-45 seconds, or until it's smooth and pourable. Evenly pour the warmed peanut butter on top of the ice cream and using a butter knife, swirl it into the ice cream. (I like to make sure I don't swirl it to much and leave big "pools" of peanut butter throughout the ice cream).
Top with remaining peanut butter cups and press gently into the ice cream. Cover with plastic wrap and freeze at least 4 hours or overnight.
Remove from freezer 5 minutes before serving.
Drizzle with chocolate sauce and a dollop of whipped cream, if desired.