Preheat your oven to 350°F (175°C). Crush Oreo cookies into fine crumbs.

Melt the unsalted butter and mix it with the cookie crumbs. Press into the bottom of a springform pan.

Bake the crust for 10 minutes, then allow it to cool.

In a mixing bowl, beat cream cheese and sugar until smooth. Add hot chocolate mix, cocoa powder, sour cream, vanilla extract, and heavy cream, mixing until combined.

Add eggs one at a time, beating on low speed after each addition.

Pour cheesecake filling over the cooled crust. Bake at 300°F (150°C) for 60-75 minutes.

Once baked, turn off the oven and leave the cheesecake inside with the door cracked for 1 hour.

Transfer the cheesecake to the refrigerator to chill overnight.

Remove from the pan, top with whipped cream, mini marshmallows, and dust with cocoa powder before serving.