Preheat your oven to 350 degrees. Spray a pie tin with nonstick cooking spray and set aside.
Combine the oreo cookie crumbs and the melted butter. Press firmly into pie tin. Bake for 10 minutes then remove and let cool completely (I let it cool on the counter for a moment before sticking it in the freezer while I made the filling).
To make the filling, combine the marshmallows and the milk in a double boiler over simmering water. Stir frequently and let the marshmallows and milk melt together. You want to make sure all the marshmallows have melted and there's no lumps.
Immediately remove the melted marshmallows and let cool for about 20 minutes.
Whip the cream into soft peaks. Fold the whipped cream into the cooled melted marshmallows and then pour this into the pie crust.
Place pie in the fridge and let it set for about two hours. Decorate the pie with chocolate shavings or chopped bittersweet chocolate!