Prepare the Crust: Preheat oven to 325°F (163°C). Grease and wrap a 9-inch springform pan in foil.
Make Crust Base: Mix chocolate wafer crumbs and melted butter, press into pan, and bake for 10 minutes. Let cool.
Melt Chocolate: Set a heatproof bowl over simmering water, add chopped chocolate, and stir until melted. Set aside.
Prepare Cheesecake Filling: Blend cream cheese, sugars, and cocoa in a food processor. Add eggs, yolks, cream, melted chocolate, and vanilla; mix until smooth.
Assemble Cheesecake: Pour filling over the crust in the pan.
Bake in Water Bath: Place the pan in a larger baking dish, add hot water around it, and bake for 1 hour and 10 minutes until center is set but jiggly.
Cool and Chill: Remove from water bath, loosen foil, run a knife around edges, and cool. Refrigerate for 6 hours.
Make Ganache: Heat cream, pour over chocolate, whisk until smooth, add butter, and stir until glossy.
Finish and Serve: Pour ganache over chilled cheesecake and let set for 1 hour. Slice with a clean knife, and enjoy!