Soften ice cream in the refrigerator until it is still frozen but soft enough to smooth into the chocolate pie crust. Fill crust, smooth top, then place back in freezer until hard.

When ice cream is hard again, heat the fudge sauce, stirring regularly, until pourable. Spread over the top of the ice cream, then freeze again until hard.

If using a whipped topping, sprinkle gelatin in cool water and let sit a few minutes to soften. Heat gelatin and water in the microwave until warm but not boiling, then stir to dissolve gelatin (this may take a minute or two). Set aside and start cream

Whip the cream on high until soft peaks form. Add powdered sugar and vanilla and whip until incorporated. With beaters running (if possible), drizzle in liquified gelatin mixture and beat until stiff peaks form.

Spoon mixture into piping bag (or zip loc with a corner cut out) fitted with a star tip. Starting from the outside, pipe stars in a circle around the edge of the pie. When finished, continue piping just inside the finished circle until the pie is covered. Place pie into freezer to freeze.

Crumble chocolate cookie part of one Oreo, then sprinkle on frozen topping. Store in freezer until time to serve. Best if taken out a couple minutes before serving to soften slightly.