01 - Preheat the oven to 325°F. Grease a 9-inch springform pan.
02 - Pulse 24 Oreo cookies into fine crumbs in a food processor. Mix with melted butter until combined. Press firmly into the bottom of the pan.
03 - Bake the crust for 10 minutes. Set aside to cool.
04 - Beat the softened cream cheese and sugar in a large bowl until smooth and creamy.
05 - Mix in the cocoa powder until well blended. Add the melted and cooled chocolate chips, mixing until combined.
06 - Add the eggs one at a time, mixing well after each. Stir in the vanilla extract and sour cream.
07 - Gently fold in the coarsely chopped Oreo cookies.
08 - Pour the filling over the cooled crust. Tap the pan to release air bubbles. Bake for 45 minutes until the center is just set.
09 - Turn off the oven, crack the door open, and let the cheesecake cool inside for 1 hour.
10 - Remove from the oven and run a thin knife around the edge. Cool completely to room temperature, then refrigerate for at least 4 hours.
11 - Heat the heavy cream in a small saucepan until just simmering. Pour over the chocolate chips and let sit for 1 minute. Stir until smooth and glossy.
12 - Spread the ganache over the chilled cheesecake. Decorate with Oreo halves or crushed cookies. Chill for 30 minutes before serving.