Prepare the crust: Add the Oreos to a food processor and process until a very fine crumb. Add in the butter, espresso powder and sea salt and process until fully combined.
Transfer the mixture to a 9-inch springform pan (a 9x9inch baking pan or deep dish pie pan can work.) Press the crust into the bottom of the pan, a little bit may come up the sides. Don’t press the mixture too hard or it will become rock solid when frozen and hard to work with. Just press until it seems even. Place in the freezer.
Make the Oreo ice cream filling: Using a standing or hand mixer, mix the whipping cream on medium-high until stiff peaks begin to form. This will take several minutes.
When stiff peaks begin to form, add in the condensed milk, sour cream, and vanilla (I like to add a sprinkle of espresso powder here as well, but optional). Mix on low speed or fold in, just until combined.
Crush the Oreos well, you want a good mix of chunks and also very small crumbs for best results. Fold them into the cream mixture very gently.
Transfer the mixture to the prepared pie crust and spread in an even layer.
Whipped cream topping: Freeze for about 1 hour before making the whipped cream topping. When the pie has set a bit, beat the whipped cream ingredients together until stiff peaks form. Spread over top of the Oreo ice cream layer evenly.
Freeze for at least 6-8 hours before serving, I usually freeze overnight. Before serving, sprinkle more crushed Oreos over top of the pie.
Use a sharp knife to slice pieces fresh from the freezer and allow the slices to sit on plates for about 10 minutes before serving to allow it to soften up a bit and get nice and creamy.