Preheat the oven to 325°F (160°C) and prepare a water bath by placing a roasting pan filled with hot water on the bottom rack.

In a mixing bowl, combine chocolate cookie crumbs with melted unsalted butter until resembling wet sand. Press into a springform pan.

Beat softened cream cheese and granulated sugar until smooth. Gradually add eggs, then mix in hot cocoa until fully incorporated.

Pour the filling over the crust and bake for 50-60 minutes until the edges are set and the center is slightly jiggly.

Turn off the oven and let the cheesecake cool inside for 1 hour. Then refrigerate for at least 4 hours or overnight.

Whip heavy cream until soft peaks form, then fold in marshmallow fluff to make the topping.

Spread the marshmallow whipped cream over the cheesecake and garnish with mini marshmallows or chocolate shavings if desired.