Preheat the oven to 325°F. Grease a 9-inch springform pan and wrap the bottom with foil.
In a bowl, combine the Graham cracker crumbs, sugar, and melted butter. Press the mixture into the bottom of the prepared pan and bake for 10 minutes. Remove from the oven and set aside to cool.
In a large bowl, beat the cream cheese until smooth. Add the sugar, eggs, and whiskey, and beat until well combined. Mix in the melted chocolate until smooth.
Pour the cheesecake filling onto the cooled crust and smooth out the top. Bake for 60-70 minutes, or until the edges are set and the center is still slightly jiggly.
Remove from the oven and run a knife around the outer edge of the cheesecake to help prevent cracks. Let cool to room temperature, then refrigerate for at least 4 hours, or overnight.
To make the caramel sauce, in a small saucepan, combine the sugar and water over medium-high heat. Cook, stirring occasionally, until the sugar has dissolved and the mixture comes to a boil.
Let the mixture boil, without stirring, until it turns dark amber in color, about 8-10 minutes. Remove from heat and add the heavy cream, butter, and salt. Whisk until smooth.
Pour the caramel sauce over the chilled cheesecake and serve.