Wrap a 9-inch springform pan tightly with plastic wrap and preheat the oven to 325°F (163°C). In a food processor, pulse chocolate graham crackers into fine crumbs and combine with melted butter until it resembles wet sand. Press firmly into the bottom of the prepared pan to form an even crust.

In a large mixing bowl, beat softened cream cheese on medium speed until smooth and creamy, about 2-3 minutes. Gradually add eggs, sugar, sour cream, mascarpone, and the dissolved instant coffee mixed with Kahlua. Mix until fully incorporated, then pour the mixture over the prepared crust. Bake for 65-75 minutes until set but slightly jiggly. Cool for one hour.

Whip heavy cream in a separate bowl until stiff peaks form, about 3-5 minutes. In another bowl, combine mascarpone, sweetened condensed milk, and melted chocolate, mixing well. Slowly add the dissolved gelatin mixture, then gently fold in whipped cream until combined. Pour the mousse evenly over the cooled cheesecake and refrigerate for 30 minutes to 1 hour until set.

Beat cream cheese, melted chocolate, Kahlua, and a pinch of salt until smooth and creamy. Add cold heavy cream and whisk until fluffy. Pipe or spoon whipped cream layer onto the coffee mousse. Refrigerate overnight for the best flavor and texture.

Run a knife around the edge of the springform pan to loosen the cheesecake. Release the sides and gently lift off the base. Keep refrigerated until ready to serve. Slice and enjoy chilled.