01 - Preheat the oven to 325°F. Grease a 9-inch springform pan and set aside.
02 - In a food processor, pulse 24 Oreo cookies into fine crumbs. Combine thoroughly with the melted butter. Press the crumb mixture firmly and evenly into the bottom of the prepared springform pan. Bake for 10 minutes, then remove and allow to cool completely.
03 - In a large mixing bowl, beat the softened cream cheese and granulated sugar together using an electric mixer until smooth and creamy. Add the cocoa powder and blend until uniformly incorporated. Mix in the melted and cooled chocolate chips until fully combined.
04 - Add the eggs one at a time, mixing thoroughly after each addition. Stir in the vanilla extract and sour cream until the batter is completely smooth.
05 - Gently fold the coarsely chopped Oreo cookies into the batter using a rubber spatula, distributing them evenly throughout.
06 - Pour the filling over the cooled crust. Gently tap the springform pan on the counter several times to release any trapped air bubbles. Bake for 45 minutes, or until the center is just barely set with a slight jiggle.
07 - Turn off the oven, crack the oven door open, and allow the cheesecake to cool gradually inside for 1 hour. This prevents cracking on the surface.
08 - Remove the cheesecake from the oven. Run a thin knife around the edges to loosen it from the pan. Allow it to cool to room temperature, then refrigerate for at least 4 hours or preferably overnight.
09 - Heat the heavy cream in a small saucepan until it just begins to simmer. Remove from heat and pour over the chocolate chips in a heatproof bowl. Let sit for 1 minute, then stir gently until the ganache is smooth and glossy.
10 - Spread the chocolate ganache evenly over the chilled cheesecake. Garnish with Oreo halves or crushed Oreo pieces. Chill for at least 30 minutes before slicing and serving.