Prep your pan. You'll need a 9" springform pan (or whatever size you have will work) and we'll be using just the ring. Toss the ring in the freezer.
Note: You could use the whole pan, but think it's simpler to use parchment paper and a flat surface rather than the base.
Remove one container of ice cream and let it soften at room temp. We don't want to melt it, we want it softened. After about 20 minutes I plop the ice cream out into a large mixing bowl. If the center is too hard to beat, I cut the ice cream into fourths and let it soften a bit more.
Beat ice cream until it is soft and creamy - like the texture of soft serve.
Remove springform from freezer. You'll want to place a piece of parchment paper on top of a flat, appropriate sized base. I use a cake carrier base - a cookie sheet, cutting board or large serving plate would work well too. Place your springform on top of parchment paper.
Scrape ice cream into springform and place in freezer.
Prep your cookie crumbs. Hopefully you won't be doing any prepping here because you bought a bag of chocolate cookie crumbs in your bulk section, but if not, get to scraping that cream out and crush the cookies.
Heat the fudge sauce up so it's easily stirred and can be poured. Try 15 seconds, stir, 10 seconds & stir (if necessary). This doesn't need to be molten lava - just barely warm and easily poured.
In a microwave safe bowl, combine peanut butter and karo syrup. Microwave for 20 seconds, stir, return to microwave for 15 seconds and stir until thoroughly combined.
Remove cake from freezer. Spread an even layer of cookie crumbs over ice cream. Drizzle chocolate fudge sauce evenly over cookie crumbs and drizzle peanut butter sauce over fudge sauce. Using a spatula or fork, gently & evenly spread/swirl fudge and peanut butter over cookie crumbs.
Cover cake (another piece of parchment paper works fine) and return to freezer. Let cake set overnight.
In the morning, remove your second container of ice cream and let it soften. Repeat process as in step 3 & 4.
Scrape ice cream on top of cookie/fudge/pb layer and evenly smooth out. Recover with parchament paper and return cake to freezer. It should sit for a few hours - at least 5-6, preferably 8. The longer, the better.
Remove parchment paper for top & bottom of cake. Remove cake from springform. I gently loosen the clamp on side and carefully wiggle & loosen sides of cake with a butter knife. I hear rubbing a hot rag on the outside of the pan helps if you're having problems, but it always releases pretty easily for me.
Using a spatula, frost cake with whipped topping - I used the whole container. Decorate with sprinkles, candy, whatever you'd like.
Return cake to freezer, covered, until ready to serve.
Let cake sit at room temp for 5 -10 minutes before cutting and serving. Cake is easily cut with a knife run under hot water.
Enjoy. Store covered in freezer.