Step 1: Prepare the Crust

1. Preheat your oven to 325°F (163°C).
2. In a medium bowl, combine the chocolate cookie crumbs, melted butter, and granulated sugar. Mix until the crumbs are evenly coated and the mixture holds together when pressed.
3. Press the mixture into the bottom of a greased 9-inch springform pan, creating an even crust. Bake for 10-12 minutes, then remove from the oven and set aside to cool.

Step 2: Make the Cheesecake Filling

1. In a large mixing bowl, beat the softened cream cheese until smooth and creamy.
2. Add the sour cream, powdered sugar, and vanilla extract, and beat until fully combined.
3. Add the eggs one at a time, mixing each in thoroughly. Then, fold in the melted chocolate and heavy cream.
4. Pour the cheesecake filling over the cooled crust, spreading it evenly.

Step 3: Bake the Cheesecake

1. Place the cheesecake in the oven and bake for 45-50 minutes, or until the edges are set but the center still has a slight wobble.
2. Turn off the oven, crack the oven door slightly, and let the cheesecake cool inside for 1 hour.
3. After 1 hour, transfer the cheesecake to the fridge to chill for at least 4 hours, preferably overnight.

Step 4: Serve

1. Once chilled, remove the cheesecake from the springform pan and place it on a serving platter.
2. Slice and serve as is, or garnish with whipped cream, chocolate shavings, or extra cookie crumbs for a decorative touch.