01 - Preheat oven to 325°F. Grease a 9-inch springform pan and line the bottom with parchment paper.
02 - Combine the crushed chocolate sandwich cookies with the melted butter until evenly moistened. Press the mixture firmly into the bottom of the prepared springform pan, creating an even layer. Bake for 10 minutes, then set aside to cool completely.
03 - Using a hand or stand mixer, beat the softened cream cheese and granulated sugar together on medium speed until completely smooth and free of lumps. Add the smooth peanut butter and blend until fully incorporated.
04 - Add the eggs one at a time, beating on low speed after each addition just until combined. Stir in the vanilla extract and sour cream, mixing gently to avoid introducing excess air.
05 - Divide the filling mixture evenly into two portions. Fold the melted dark chocolate into one half, stirring until uniform in color. Leave the other half as the plain peanut butter mixture.
06 - Pour the chocolate batter over the cooled crust and spread into an even layer. Spoon the peanut butter batter on top in dollops. Run a butter knife through both layers in gentle swirls to create a marbled pattern.
07 - Bake for 50 to 60 minutes, until the edges are set and the center has a slight jiggle when gently shaken. Avoid overbaking to maintain a creamy texture.
08 - Turn off the oven, crack the door open slightly, and allow the cheesecake to cool inside for 1 hour. This gradual cooling prevents cracking on the surface.
09 - Transfer the cheesecake to the refrigerator and chill for at least 4 hours or overnight for the best set and flavor development.
10 - Heat the heavy cream in a small saucepan until steaming but not boiling. Remove from heat, add the chopped dark chocolate, and stir until glossy and smooth. Stir in the creamy peanut butter until well blended. Let the ganache cool slightly until it thickens to a spreadable consistency.
11 - Spread the ganache topping evenly over the chilled cheesecake. Garnish with chopped roasted peanuts if desired. Slice with a warm, clean knife and serve.