Ultimate Chocolate Cheesecake

For the Ultimate Chocolate Cheesecake:

Fill a medium pot one-third full with water and bring it to a low simmer over medium heat.
Place a heatproof bowl that will fit on top of the pan snugly, but will not touch the simmering water, on top of the pan. Reduce the heat to low and add the chopped chocolate into the bowl over the pot. Heat until the chocolate is completely melted, stirring occasionally with a silicon spatula. Remove the pot from the heat, leaving the bowl of chocolate over the hot water. Set aside until needed.
In the bowl of a food processor (or high-powered blender), pulse the cream cheese until completely smooth, scraping down the sides of the bowl as needed, about 2 minutes. Add in both sugars and cocoa powder and beat smooth. Add in the eggs, egg yolks, and heavy cream and mix until just combined, about 20 seconds. Fold in the chocolate. Finally add in the vanilla and pulse for another 20 seconds.
Remove the bowl from the food processor and, using a rubber spatula, stir the filling several times to ensure it’s evenly blended.
Scrape the filling over the partially baked crust in the prepared pan.
Place the springform pan in a roasting pan or large baking pan. Place the roasting pan in the preheated oven and pour enough hot water into the pan to come 1-inch up the sides of the springform pan.
Bake the cheesecake in the water bath for 1 hour and 10 minutes, or until the center of the cake is set but still slightly jiggly. The cake will set completely as it cools.
Remove the cake from the water bath and place the pan on a wire rack. Carefully loosen the foil, then immediately run the tip of a knife around the sides of the pan, to prevent the top from cracking. Cool completely (in the pan), then transfer cheesecake to the refrigerator to chill for at least 6 hours before removing from the pan and slicing.

For the Chocolate Ganache:

Add chopped chocolate to a medium bowl; set aside.
In a small saucepan over medium-heat, bring the cream to a low simmer. Pour half of the cream on top of the chocolate pieces and set aside for 1 minute. With a whisk, begin to incorporate the melted chocolate into the cream. Slowly add the remaining cream and continue carefully whisking until smooth and glossy.
Add in the butter and use a spatula to stir until the butter is completely melted. The mixture will be dark and glossy. Set aside, at room temperature, until needed.
Pour ganache over cooled cheesecake. Set aside until ganache is set, about 1 hour.
To serve, slice the cheesecake with a thin-bladed sharp knife, wiping the knife clean between each cut.
Store, loosely covered, in the refrigerator, for up to 5 days.