01 - Preheat oven to 325°F (160°C). Grease and line a 9-inch springform pan.
02 - Pulse ladyfingers into fine crumbs using a food processor. Combine crumbs with melted butter and espresso powder until evenly moistened. Press mixture firmly into the bottom of the prepared pan. Bake for 10 minutes, then allow to cool completely.
03 - In a small bowl, combine hot espresso, granulated sugar, and coffee liqueur (if using). Stir until sugar dissolves, then set aside to cool.
04 - In a large mixing bowl, beat softened cream cheese, mascarpone, and sugar with an electric mixer until smooth and creamy. Add eggs one at a time, mixing thoroughly after each addition. Incorporate cooled brewed espresso, vanilla extract, flour, and a pinch of salt. Mix only until combined; do not overbeat.
05 - Brush or drizzle half of the prepared coffee soak evenly over the cooled crust.
06 - Pour the cheesecake batter gently over the soaked crust. Tap the pan lightly to release air bubbles. Place pan in a water bath and bake for 60 minutes, or until the center is just set with a slight jiggle. Turn off the oven, crack the door open, and let the cheesecake cool inside for 1 hour.
07 - Remove cheesecake from oven and cool to room temperature. Refrigerate for at least 4 hours or overnight until thoroughly chilled.
08 - In a chilled bowl, whip heavy cream with powdered sugar and vanilla extract to stiff peaks.
09 - Carefully release cheesecake from the pan. Optionally, brush or drizzle remaining coffee soak on the top for enhanced flavor. Evenly spread whipped cream over the cheesecake, dust generously with cocoa powder, and garnish with dark chocolate shavings if desired. Slice and serve thoroughly chilled.