In a food processor, pulse Oreo cookies, including center filling, until crumbly like a sand texture. Add melted butter and pulse until well combined.
Press cookie mixture into bottom and sides of 9 inch pie plate. Set aside. (I like to prepare the pan and grease it or spray with non-stick spray to ensure no possibility of sticking.)
Filling
Whisk sugar, cocoa, espresso powder, cornstarch and salt together in a medium to large pot.
With pot over medium heat, slowly add milk while stirring until smooth with no lumps remaining.
Bring it to a boil over medium heat for two minutes as it starts to thicken to a pudding like texture. Stir constantly.
Add butter and vanilla and whisk until well combined.
Remove from heat and whisk in cream (it is important to remove from the heat or the cream will split.)
Pour thickened filling into pie crust. Place crumbled Oreos all over top. The crumbles should sit on top of the filling and not sink.
Place pie into the freeze for 4 hours or up to over night. Do not cover or steam and icicles will form. After the pie is completely cold, you can cover to store in the freezer for longer periods of time. Before serving allow pie to sit out for about 5 minutes, this will make cutting into slices easier. Enjoy!