01 - Preheat oven to 325°F. Grease and line a 9-inch springform pan.
02 - Pulse ladyfingers into fine crumbs in a food processor. Combine with melted butter and espresso powder until mixture is evenly moistened. Press firmly into the bottom of the prepared pan.
03 - Bake crust at 325°F for 10 minutes, then set aside to cool completely.
04 - Stir hot espresso, granulated sugar, and coffee liqueur (if using) together until sugar dissolves. Set aside to cool.
05 - In a large bowl, blend cream cheese, mascarpone, and sugar using an electric mixer until completely smooth. Beat in eggs one at a time, ensuring each is incorporated before adding the next. Mix in brewed espresso, vanilla extract, flour, and salt, mixing only until just combined.
06 - Brush or drizzle half of the prepared coffee soak evenly over the cooled crust.
07 - Pour the cheesecake filling over the crust. Tap the pan gently on the counter to remove air bubbles.
08 - Place the springform pan into a larger baking dish and add hot water halfway up the sides to create a water bath. Bake at 325°F for 60 minutes, or until the center looks just set but still jiggles slightly. Turn off the oven, crack the door open, and let the cheesecake cool inside for 1 hour.
09 - Remove cheesecake from oven. Cool to room temperature, then refrigerate for at least 4 hours or overnight until fully set.
10 - Whip heavy cream with powdered sugar and vanilla extract to stiff peaks using an electric mixer.
11 - Release cheesecake from pan. Optionally brush or drizzle remaining coffee soak over the surface. Smooth the whipped cream topping over the cake, then dust generously with cocoa powder and finish with chocolate shavings if desired. Slice and serve chilled.