Prepare the Crust:

1. Preheat the Oven: Preheat your oven to 325°F (160°C). Grease the bottom and sides of a 9-inch springform pan with butter or non-stick spray.
2. Mix the Crust Ingredients: In a medium bowl, combine the chocolate cookie crumbs, sugar, and melted butter. Stir until well combined and the crumbs are evenly coated with butter.
3. Press the Crust into the Pan: Press the cookie mixture into the bottom of the prepared pan, using the back of a spoon to pack it firmly and evenly.
4. Bake the Crust: Bake the crust in the preheated oven for 10 minutes, then remove it from the oven and set aside to cool.

Prepare the Filling:

5. Melt the Chocolate: In separate bowls, melt the dark chocolate and milk chocolate. You can melt them in the microwave in 20-second intervals, stirring in between, or use a double boiler.
6. Mix the Cream Cheese and Sugar: In a large mixing bowl, beat the softened cream cheese and granulated sugar with an electric mixer until smooth and creamy.
7. Add the Eggs: Add the eggs one at a time, beating well after each addition until fully incorporated.
8. Add the Vanilla and Sour Cream: Stir in the vanilla extract and sour cream until fully combined.
9. Add the Melted Chocolate: Gradually add the melted dark chocolate and milk chocolate to the cream cheese mixture, mixing until smooth and well incorporated.
10. Pour the Filling into the Crust: Pour the cheesecake filling over the cooled cookie crust, smoothing the top with a spatula.
11. Bake the Cheesecake: Bake in the preheated oven for 55-60 minutes, or until the edges are set and the center is slightly jiggly. The cheesecake will continue to set as it cools.
12. Cool and Chill: Allow the cheesecake to cool in the pan at room temperature for 1 hour. Then, cover and refrigerate for at least 4 hours, or overnight for the best results.

Prepare the Ganache:

13. Melt the Ganache Ingredients: In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer. Remove from the heat and add the chopped milk and dark chocolate. Stir until the chocolate is completely melted and the ganache is smooth.
14. Cool the Ganache: Let the ganache cool for a few minutes until it thickens slightly but is still pourable.

Assemble and Garnish:

15. Pour the Ganache: Once the cheesecake is fully chilled, pour the ganache over the top, spreading it evenly with a spatula to cover the entire surface.
16. Chill Again: Refrigerate the cheesecake for an additional 30 minutes to allow the ganache to set.
17. Garnish and Serve: Optionally, garnish with chocolate shavings or curls and a dollop of fresh whipped cream before serving. Slice into 12 servings and enjoy!