Preheat your oven to 325°F (160°C). Blend Oreo cookies into fine crumbs and combine with melted butter until evenly mixed. Press this mixture into the base and sides of a greased 9-inch springform pan. Bake for 11 minutes, then cool.

In a large bowl, beat cream cheese and granulated sugar on medium speed until smooth. Gradually mix in hot cocoa mix, cocoa powder, sour cream, heavy cream, and vanilla extract. Add eggs one at a time, mixing on low speed.

Place the springform pan inside a large roasting pan. Fill with hot water halfway up the sides of the springform pan. Bake for 75-85 minutes until the edges set and the center jiggles. Let it cool in the oven for 30 minutes.

Transfer the cheesecake to a cooling rack, let it sit until room temperature, then chill covered in the fridge for at least 6 hours. Whip heavy cream with powdered sugar until medium peaks form and spread over the cheesecake before serving.