Prepare the Crust:
Preheat the oven to 325°F (163°C). In a bowl, combine the chocolate cookie crumbs, melted butter, and granulated sugar. Mix until the crumbs are evenly coated. Press the mixture into the bottom of a 9-inch springform pan, creating an even crust. Bake for 10-12 minutes, then remove from the oven and let it cool.
Make the Cheesecake Filling:
In a large mixing bowl, beat the cream cheese until smooth. Add the sour cream, granulated sugar, and vanilla extract, and mix until smooth. Add the eggs, one at a time, beating well after each addition. Finally, add the flour and mix until fully combined.
Assemble the Cheesecake:
Pour the cheesecake filling into the cooled crust, smoothing the top with a spatula. Tap the pan to remove any air bubbles. Bake for 55-65 minutes or until the cheesecake is set but still slightly wobbly in the center. Turn off the oven and let it cool in the oven for 1 hour with the door ajar. Refrigerate for at least 4 hours, or overnight.
Make the Caramel Sauce:
In a medium saucepan, combine the heavy cream, brown sugar, and butter. Cook over medium heat, stirring constantly. Once the mixture comes to a simmer, cook for 5-7 minutes until thickened. Stir in the vanilla extract and salt, then remove from heat. Let it cool to room temperature.
Top the Cheesecake:
Once the cheesecake has chilled, pour the caramel over the top, spreading it evenly. Melt the dark chocolate and butter in the microwave in 20-second intervals, stirring until smooth. Drizzle the melted chocolate over the caramel layer.
Serve:
Allow the cheesecake to chill for another 30 minutes to let the chocolate set. Slice and serve chilled.