Preheat your oven to 325 degrees Fahrenheit (163 degrees Celsius). Grease the sides of a 9.5-inch springform pan with nonstick baking spray.

In a food processor, pulse the Oreo cookies until they form fine crumbs. Alternatively, crush the cookies in a bag with a rolling pin. Add melted butter to the crumbs and pulse to combine.

Press the cookie mixture evenly into the bottom of the prepared pan. Bake for 10 minutes, then set aside to cool.

In a bowl, mix cocoa powder and sugar to prevent lumps. In a large bowl, beat cream cheese until smooth. Add the cocoa-sugar mixture and beat until combined.

In a microwave-safe bowl, heat 1/2 cup heavy cream and melted chocolate in 30-second intervals until smooth. Add this to the cream cheese mixture and beat until fully incorporated.

Add vanilla extract, then eggs one at a time, beating well after each addition. Mix in sour cream until combined.

Wrap the springform pan with two layers of heavy-duty foil. Place the pan in a larger pan with an inch of water. Pour the cheesecake batter over the crust.

Bake for 1 hour 20 minutes to 1 hour 30 minutes until the center slightly jiggles. Turn off the heat, crack the oven door, and let the cheesecake cool in the oven for 1-2 hours. Chill in the fridge overnight.

For the ganache, microwave chocolate chips and 1/2 cup heavy cream until smooth. Pour over the cooled cheesecake and sprinkle with chocolate curls.

For the chocolate whipped cream, melt 2 tablespoons of heavy cream with chocolate, then let cool. Beat the remaining cream until soft peaks form. Fold in the chocolate mixture until combined.

Pipe the whipped cream on top of the chilled cheesecake in swirls.

Slice and enjoy! Store any leftovers in the fridge.