01 - Preheat the oven to 325°F. Grease a 9-inch springform pan and line the base with parchment paper.
02 - Combine the crushed chocolate sandwich cookies with the melted butter until the mixture resembles wet sand. Press firmly and evenly into the bottom of the prepared pan. Bake for 10 minutes, then set aside to cool slightly.
03 - Using an electric mixer on medium speed, beat the softened cream cheese and granulated sugar together until completely smooth and free of lumps. Add the peanut butter and sour cream, blending until fully incorporated.
04 - Add the eggs one at a time, mixing on low speed just until each is incorporated. Stir in the vanilla extract. Avoid overmixing to prevent excess air in the batter.
05 - Pour half of the filling over the baked crust. Drizzle half of the melted dark chocolate over the surface and gently swirl with a butter knife. Add the remaining batter and repeat with the remaining melted chocolate, creating a marbled effect.
06 - Bake on the center rack for 50 to 55 minutes, until the edges are set but the center still has a slight jiggle. Turn off the oven, crack the door open, and let the cheesecake cool inside for 1 hour to prevent cracking.
07 - Remove the cheesecake from the oven and transfer to the refrigerator. Chill for at least 4 hours, or preferably overnight, until fully set.
08 - Heat the heavy cream in a small saucepan until hot but not boiling. Pour over the finely chopped dark chocolate and let stand for 2 minutes. Stir until smooth and glossy, then blend in the peanut butter.
09 - Spread the ganache evenly over the chilled cheesecake. Allow it to set for at least 30 minutes before slicing and serving.