Preheat your oven to 350°F (180°C). Grease a 9-inch springform pan with butter and line the bottom with parchment paper.

In a medium saucepan, melt the cubed unsalted butter over low heat. Remove and mix in granulated and brown sugar until combined. Add eggs and vanilla, blend well. Sift in flour, cocoa powder, and salt.

Pour the brownie batter into the prepared pan and bake for 20-25 minutes. Let cool completely.

Beat cream cheese until creamy. Gradually add granulated sugar and cornstarch, mix well. Add sour cream, vanilla extract, and heavy cream.

Dissolve instant coffee in hot water and add to the filling. Add eggs one at a time, mixing gently.

Pour cheesecake filling over the cooled brownie base.

Wrap the springform pan in aluminum foil and place it in a larger dish filled with hot water.

Bake the cheesecake at 300°F (150°C) for about 1 hour and 15 minutes. Turn off oven and let it cool for 30 minutes.

Heat heavy cream for ganache until steaming, stir in coffee granules. Pour over chocolate chips to create ganache.

Refrigerate cheesecake overnight. Before serving, garnish with ganache and chocolate curls.