Crush the Oreos: Pulse the Oreo cookies in a food processor or blender until you have coarse crumbs with a few larger chunks. You should end up with about 1 cup of crumbs. Transfer to a bowl.
10 Oreo cookies
Make the Oreo crunch layer: Stir the melted butter into the Oreo crumbs until evenly coated. The mixture should look slightly damp and crumbly. Set aside.
2 tablespoons unsalted butter melted
Prep the pan: Line a 9x3-inch springform pan with plastic wrap, leaving overhang on all sides so the cake can be lifted out easily later.
Layer the first ice cream: Let the chocolate ice cream sit at room temperature for about 10 minutes until scoopable but still firm. Spoon it into the lined pan and quickly spread into an even layer using the back of a large spoon. Freeze for 30 minutes.
1 1/2 quarts chocolate ice cream softened
Add fudge and Oreo crunch: Warm the hot fudge just until spreadable, not hot. Spread 1/2 cup of the fudge evenly over the frozen ice cream layer, then sprinkle the Oreo mixture evenly on top. Freeze for another 30 minutes.
1 cup hot fudge sauce divided
Soften the top ice cream: About 20 minutes into the freeze time, remove the strawberry ice cream from the freezer and let it soften for 10 minutes so it spreads easily without melting.
1 1/2 quarts strawberry ice cream softened
Layer fudge and top ice cream: Spread the remaining 1/2 cup hot fudge over the Oreo layer. Spoon the softened strawberry ice cream on top and spread into an even layer. Cover with plastic wrap or foil and freeze for at least 12 hours and up to 2 days.
Freeze the serving plate: If serving on a plate or cake stand, place it in the freezer for at least 30 minutes so the cake doesn’t melt on contact.
Whip the topping: Beat the heavy cream, powdered sugar, and vanilla on medium-high speed until stiff peaks form, about 4 minutes.
2 cups cold heavy cream, 1/3 cup powdered sugar, 1 1/2 teaspoons vanilla extract
Unmold and frost: Remove the cake from the freezer and release the springform rim. Lift the cake out using the plastic wrap and peel it away. Place the cake on the frozen plate or pan base and quickly frost the top and sides with whipped cream. Add sprinkles if desired.
Sprinkles optional
Slice and serve: For clean slices, cut with a sharp knife dipped in hot water between cuts. Serve immediately or within 1 hour for best texture. Keep leftovers covered in the freezer.