Preheat your oven to 300°F (150°C) and gather four ramekins. Place them in a 9x9 baking pan, ensuring they fit snugly. Boil water in a separate kettle.

In a medium saucepan over medium heat, combine the heavy cream, granulated sugar, and a pinch of kosher salt. Stir constantly until the sugar dissolves and the mixture is heated through but not boiling, about 5 minutes.

In a large mixing bowl, whisk together the egg yolks until smooth and slightly thickened. Slowly pour the warmed cream mixture into the yolks, whisking constantly to prevent curdling.

In a small bowl, dissolve the instant espresso powder and Kahlúa together. Stir this mixture into the custard blend, incorporating all the flavors harmoniously, then strain the mixture through a fine mesh sieve.

Carefully divide the custard mixture among the ramekins, filling them evenly. Pour the hot water into the baking pan until it reaches halfway up the sides of the ramekins. Bake for 25-35 minutes until the custards are set but slightly jiggly in the center.

Remove the ramekins from the water bath and let them cool at room temperature for about 4 hours. Cover with plastic wrap and refrigerate until ready to serve.

Just before serving, evenly sprinkle a thin layer of granulated sugar over the top of each chilled custard. Using a kitchen torch, caramelize the sugar until it forms a golden brown, crunchy crust.