Preheat the oven to 350°F (175°C). Grease a 9-inch springform pan and line the bottom with parchment paper for easy removal.
In a medium bowl, combine the Oreo cookie crumbs with the melted butter. Stir until the crumbs are evenly coated with the butter and have a texture like wet sand.
Press the crumb mixture into the bottom of the prepared springform pan, spreading it out to form an even layer. Use the bottom of a glass or a flat measuring cup to press the crumbs firmly into place.
Bake the crust in the preheated oven for 8-10 minutes until set. Remove from the oven and let it cool while you prepare the cheesecake filling.
Step 2: Make the Cheesecake Filling
In a large mixing bowl, beat the softened cream cheese with an electric mixer on medium speed until smooth and creamy, about 2-3 minutes.
Add the granulated sugar and flour, and continue to beat until well combined, scraping down the sides of the bowl as needed.
Add the vanilla extract and one egg at a time, mixing on low speed after each addition until just combined. Be careful not to overmix, as this can incorporate too much air into the batter.
Pour in the melted dark chocolate and Kirsch (cherry liqueur), and gently fold into the cream cheese mixture until the batter is smooth and well-blended.
Finally, add the sour cream and stir until incorporated. The sour cream will give the cheesecake a smooth, creamy texture.
