Preheat your oven to 350°F (175°C) and prepare your springform pan by greasing it lightly.

In a mixing bowl, combine the chocolate graham cracker crumbs, melted unsalted butter, and granulated sugar. Press into the bottom of the springform pan.

Bake the crust for about 10 minutes until set, then let it cool.

In a separate bowl, beat softened cream cheese until smooth. Gradually mix in sour cream and heavy cream.

Sift in cocoa powder and granulated sugar while mixing on low speed until smooth.

Add eggs one at a time, mixing on low speed just until combined.

Pour the cheesecake filling over the cooled crust, level it off, and bake for 55-65 minutes.

Turn off the oven and let the cheesecake cool inside for about one hour.

Prepare the ganache by heating heavy cream, pouring it over dark chocolate, and stirring until smooth.

Pour ganache over cooled cheesecake, cover with plastic wrap, and refrigerate for at least 4 hours.