Prepare a 9-inch springform pan with plastic wrap, set aside.
Crush chocolate sandwich cookies in food processor, blender, or using the sandwich bag method.
Heat ½ cup hot fudge in microwave for 15-20 seconds, then stir and immediately mix into crushed cookies, set aside.
Remove lid of jar of hot fudge and microwave for 20 seconds, stir well, and set aside.
Stir chocolate ice cream until smooth, then using a spatula, spread into prepared pan. Freeze for 20 minutes.
Spread hot fudge over top of chocolate layer.
Sprinkle cookie mixture over top of fudge layer and press into fudge until single layer.
Freeze for 20 minutes.
Remove vanilla ice cream from freezer and allow to soften slightly.
Stir vanilla ice cream until smooth, the spread over top of cookie layer.
Freeze for at least 4 hours, overnight is best.
Once cake is frozen, prepare the frosting.
Add 1 container softened whipped topping to a mixing bowl or bowl of a stand mixer. Add powdered sugar and cream of tartar and mix until just combined, about 1 minute, then add to piping bag.
Spread the second container of whipped topping onto the top and sides of cake, smoothing with a spatula or icing smoothing tool.
Pipe around the top of the cake, the decorate with sprinkles of choice and maraschino cherries.
Cut and serve immediately or freeze until ready to serve.