In a food processor grind the graham crackers into crumbs. In a mixing bowl combine the crumbs, sugar, and 5 tablespoons of the melted butter. Pour the mixture into a parchment paper lined springform pan. Using the back of a measuring cup or flat bottomed glass to make an even layer. Bake for 10 minutes. While the crust is baking bring a tea pot of water to a boil.
Reduce the temperature to 300°F or gas mark 2.
In a stand mixer with the paddle attachment beat the cream cheese until light and add the sugars. One at a time add the eggs and beat for a minute between each egg. Scrape down the side as needed. Add the cocoa powder, melted chocolate, salt, coffee, espresso powder, and sour cream.
Use remaining tablespoon of butter and brush the sides of the springform pan and dust with a little flour. Pour the cheesecake batter into the pan. Line the entire pan with foil, place in the roasting pan and fill the pan up with the boiling water. Bake for an hour or until when the cheesecake is tapped only the center has a slight wobble.
Turn off the oven and crack the door open using a wooden spoon. Allow the oven to cool completely before removing it from the oven. Allow to cool to room temperature. Place the cheesecake in the refrigerator for a minimum of 5 hours or overnight.
When the cheesecake is cold prepare the ganache by heating the cream to boiling either in the microwave in a heat proof glass or on the stove. Pour over the chocolate and let rest for 5 minutes. Then stir. Add the powdered sugar.
Pour the ganache over the cheesecake preventing it from dripping down the sides. Remove from the springform pan.
In a stand mixer with the whisk attachment whip the remaining ingredients together. Place into a piping bag and pipe the whipped cream around the outside of the cheesecake.