1-Start by preheating the oven to 325°F (163°C) and preparing a 9 or 10-inch springform pan by lining the bottom with parchment paper and greasing the sides. This sets the stage for a smooth baking experience.

2-Next, combine the Oreo crumbs and melted butter thoroughly, then press the mixture firmly into the pan to form the crust and set it aside. Don’t forget to place a pan filled with water in the oven to add moisture, which helps prevent cracking. In a mixer with a paddle attachment, beat the cream cheese, sour cream, and sugar for 2 minutes until smooth, then add the cocoa powder, espresso powder, and vanilla extract.

3-Incorporate the eggs one at a time, mixing just until combined, followed by the melted bittersweet chocolate until everything blends smoothly. Pour the batter over the crust and tap the pan on the counter to release air bubbles. Bake on the middle rack for 55 minutes, rotating the pan halfway through; the center should remain slightly wobbly when done.

4-Turn off the oven and partially open the door, leaving the cheesecake inside to cool gradually for 1 hour. Remove it from the oven, run a knife around the edges, and let it cool at room temperature for another hour. Cover with foil and refrigerate overnight to set fully.

5-Before serving, remove the springform pan ring carefully. To prepare the ganache, heat the heavy cream until hot, pour it over the chopped chocolate, wait 1 minute, then whisk until smooth and glossy. Reserve one-third of the ganache in the refrigerator for piping, pour the rest over the chilled cheesecake, and refrigerate for 10 minutes to set. Finally, pipe decorative designs around the edge using the chilled ganache and optionally decorate with chocolate sprinkles or shavings, then slice into 16 servings.