01 - Preheat oven to 325°F (160°C). Grease and line a 9-inch springform pan with parchment paper.
02 - Pulse ladyfinger biscuits into fine crumbs using a food processor. In a mixing bowl, combine biscuit crumbs with melted butter and instant espresso powder until the mixture is evenly moistened.
03 - Press crumb mixture firmly and evenly into the base of the prepared springform pan. Bake for 10 minutes, then remove and allow to cool.
04 - In a small bowl, stir together hot espresso, coffee liqueur (if using), and granulated sugar until dissolved. Let cool to room temperature.
05 - Beat softened cream cheese, mascarpone cheese, and granulated sugar with an electric mixer until completely smooth. Add eggs one at a time, beating well between each addition. Blend in cooled brewed espresso, vanilla extract, flour, and salt just until combined.
06 - Brush or drizzle half of the cooled coffee soak evenly over the baked crust.
07 - Pour cheesecake filling onto the soaked crust. Gently tap the pan on the countertop to release air bubbles. Place pan in a larger baking dish and fill dish with hot water halfway up the sides (water bath). Bake for 60 minutes or until the center is just set with a slight jiggle.
08 - Turn off the oven and crack the oven door open. Allow cheesecake to cool inside the oven for 1 hour to prevent cracking.
09 - Remove cheesecake from oven and cool completely at room temperature. Cover and refrigerate for at least 4 hours or overnight.
10 - Whip heavy cream, powdered sugar, and vanilla extract together until stiff peaks form.
11 - Release chilled cheesecake from the pan. Brush or drizzle the remaining coffee soak over the top if desired. Spread whipped cream evenly over the surface, dust generously with unsweetened cocoa powder, and garnish with chocolate shavings if using. Slice with a clean, sharp knife and serve chilled.