Start by crushing the Oreo cookies finely using a food processor or blender. Transfer the crushed Oreos to a large bowl, add the melted butter, and mix thoroughly until the crumbs are evenly coated.

Spray the bottom and sides of a 10-inch spring form pan with nonstick spray. Press the Oreo crumb mixture firmly into the bottom of the pan and slightly up the sides to create a crust.

Place the crust in the freezer to chill for at least 15 minutes. Meanwhile, set one container of vanilla ice cream out to soften at room temperature for about 10-15 minutes.

Once the crust is firm, spread the softened ice cream evenly over it. Return the pan to the freezer and chill for 1 hour.

Warm the hot fudge topping in the microwave just enough to make it easy to spread. Spoon it over the ice cream layer, reserving about a quarter of the fudge for later use. Sprinkle half of the chopped mini peanut butter cups over the fudge layer. Freeze again for 1 hour.

Soften the second container of ice cream at room temperature. Spread it evenly over the peanut butter cups layer, smoothing it out. Freeze until firm (at least 1 hour).

To remove the cake from the pan, dip a knife in hot water and run it around the edges of the spring form pan, then unlatch and remove the sides. Use a knife or offset spatula dipped in hot water to smooth the top of the ice cream cake.

Spoon the reserved hot fudge into a plastic bag, snip off a corner, and drizzle the fudge over the top of the cake in a crosshatch pattern. Sprinkle the remaining chopped peanut butter cups on top. Freeze the cake until ready to serve.