Prepare the Crust: Preheat your oven to 325°F (163°C). Mix chocolate cookie crumbs with melted butter until well combined. Press the mixture firmly into the bottom of a 9-inch springform pan. Bake for 10 minutes, then let cool.
Make the Cheesecake Filling: In a large bowl, beat cream cheese and sugar until smooth. Add eggs one at a time, mixing on low speed until combined. Stir in vanilla, sour cream, and heavy cream.
Melt the Chocolate: Gently melt the semisweet chocolate and let it cool slightly. Fold it into the cheesecake batter until fully incorporated.
Bake the Cheesecake: Pour the batter over the cooled crust. Wrap the bottom of the springform pan with foil and place it in a larger baking pan. Fill the outer pan with hot water halfway up the sides to create a water bath. Bake for 55-60 minutes, or until the edges are set but the center is slightly jiggly.
Cool & Chill: Turn off the oven and let the cheesecake cool inside with the door slightly open for 1 hour. Then refrigerate for at least 4 hours or overnight.
Make the Caramel Sauce: In a saucepan over medium heat, dissolve sugar in water and cook until it turns a deep amber color. Remove from heat and carefully stir in heavy cream, butter, and salt. Let cool slightly.
Assemble & Serve: Drizzle the cooled caramel sauce over the cheesecake. Slice and enjoy!