1 and ½quarts(1.41L) cookies and cream ice creamalso known as a "half gallon"
10ounces (300g) hot fudgeabout 1 cup; store bought is fine
½cup(120mL) heavy cream
Use a food processor or blender1 to process Oreos into a fine crumb.
Turn the processor or blender off, add the butter, then pulse a few times until everything is blended well. Alternatively, you can add the Oreo crumbs to a bowl and mix the butter in with a large spatula. Mixture will be coarse and crumbly.
Use your hands to press the mixture evenly into the bottom and slightly up the sides of a pie dish (this crust is enough for a 9" or 10" pan). Once it is evenly spread into the dish, use the bottom of a flat measuring cup to make the crust tight and compact in the dish. Crust will be thick. Chill in the refrigerator or freezer for 30 minutes.
When there is about 15-20 minutes left for your Oreo crust, set out your cookies and cream ice cream.
When you are able to stir the ice cream fairly easily, mix it up well and then pour it into the chilled Oreo crust. Chill in the freezer for at least 1 hour.
Warm the hot fudge sauce until it is pourable but not too hot. Pour the hot fudge evenly over the chilled ice cream, then spread evenly with a rubber or offset spatula. Chill in the freezer for at least 30 minutes.
When the hot fudge layer is set, prepare the homemade whipped cream2. Pour the heavy whipping cream, sugar, and vanilla extract into the bowl of a stand mixer fitted with the whisk attachment.
Turn the mixer to medium speed. The mixture will start to get frothy and bubbly. After about 2 to 3 minutes, the mixture will start to thicken. Once mixture is visibly thick (you will be able to see the trail of the whisk), increase the speed to medium-high and beat for an additional 30 seconds to 1 minute. At this point, your whipped cream should start to look "billowy" and the trails from your whisk will be quite distinct.
Pull the whisk out of the bowl and check that the whipped cream in the bowl has formed what are called "stiff peaks." This is just a fancy term for "the whipped cream stays standing up when you pull something out of it."
Use a spatula to smooth the whipped cream topping over the firm hot fudge layer, then sprinkle the chopped Oreos evenly over the whipped cream layer, pressing down gently on the pieces to secure them in place. Place ice cream cake in the freezer for 4-6 hours (or ideally overnight).
When you are ready to serve the cake, allow to sit at room temperature for about 15-20 minutes. Run a warm butter knife around the sides of the cake to release it from the springform pan, then remove the outer ring. Use a very sharp knife to slice the cake (I find a knife run under hot water and then dried off works best here). Cover leftovers and store in the freezer up to 1 month.
Crushed Oreos: I find it easiest to put the Oreos into a food processor than to do this step by hand.
Homemade whipped cream: if you need some visuals on making whipped cream, see this post on homemade whipped cream as a guide.