Preheat your oven to 325°F (163°C) and prepare a 9-inch springform pan by greasing and wrapping it in aluminum foil.

Combine chocolate wafer crumbs with melted unsalted butter in a mixing bowl and press firmly into the bottom of the springform pan. Bake for 10 minutes and allow to cool.

Melt bittersweet chocolate using a double boiler until smooth and set aside to cool slightly.

Blend room temperature cream cheese in a food processor until smooth, then add granulated sugar, light brown sugar, and cocoa powder, mixing until combined.

Incorporate room temperature eggs and heavy cream, blending until creamy and lump-free.

Fold in melted chocolate and vanilla extract carefully.

Pour the filling into the cooled crust and tap to release air bubbles.

Prepare a water bath by placing the filled springform pan in a larger pan with hot water halfway up the sides and bake for 1 hour and 10 minutes.

After baking, crack the oven door and allow the cheesecake to cool for 1 hour, then refrigerate for at least 6 hours or overnight.

To prepare the ganache, heat additional heavy cream until simmering, pour over chopped semi-sweet chocolate, and whisk until smooth. Stir in unsalted butter.

Pour the ganache over the chilled cheesecake and let it set at room temperature for 1 hour before slicing.

Slice the cheesecake with a warm knife and serve with whipped cream or fresh fruit sauce.