Preheat oven to 350ºF. Butter a 9-inch pie shell and set aside.
Combine cookie crumbs, melted butter and sugar in a bowl until blended and moist. Press into bottom and up sides of pie shell. Bake for 12 minutes. Remove and place baked shell in freezer to chill.
Add 2 cups softened vanilla ice cream to chilled pie shell and smooth out top. Sprinkle caramel sauce over ice cream. Return to freezer for 30 minutes.
Stir softened Nutella into 2 cups of remaining softened vanilla ice cream (I usually place the Nutella in the microwave and cook on high for 20-30 seconds. Not until it's fully liquid, just smooth enough to stir easily). Spread over chilled pie, and smooth surface. Drizzle with melted chocolate and return to the freezer to fully set for 6 hours.