Remove ice cream carton from freezer and let soften for about 5 minutes.
Melt butter in microwave safe bowl.
Place chocolate wafer cookies in a clear plastic locking bag. Using a rolling pin, crush cookies into a fine meal.
In a 9" circular pan add cookie crumbs and melted butter. Press into the bottom of pan to form crust.
Chocolate whipped cream: In a large bowl, mix whipping cream, cocoa and powdered sugar on medium-high speed for about 5 minutes or until stiff peaks form.
Using a rubber spatula, spread chocolate ice cream into pan and smooth top evenly. Place chocolate whipped cream into a piping bag and decorate pie with large dollups, until covered.
Sprinkle with crushed pistachios. Freeze pie for 1 hour to set before serving.