Finely crush the chocolate sandwich cookies in a food processor or blender. Mix in the melted butter until evenly combined. Press the mixture into the bottoms and up the sides of a deep dish pie plate (9.5"x 2") or a Springform pan evenly and firmly. Chill the crust for at least 30 minutes.

Meanwhile, over a double boiler melt the marshmallows and the milk together, stirring frequently. Once the marshmallows are all melted remove the bowl from the double boiler and stir in the chopped chocolate until it’s melted and smooth. Allow the chocolate mixture to cool to room temperature, stirring occasionally.

Once the chocolate is cooled, place the heavy cream in the bowl of your stand mixer fitted with the whisk attachment. Beat the cream on medium high speed for 1-2 minutes until stiff peaks form. Fold the whipped cream into the cooled chocolate until it’s evenly combined.

Pour the mixture into the chilled crust.

Cover and chill the pie for at least 2 hours.

When you’re ready to serve it you can garnish it with extra whipped cream, if desired.