01 - Preheat oven to 325°F (160°C). Grease and line a 9-inch (23 cm) springform pan with parchment paper.
02 - Pulse ladyfinger biscuits into fine crumbs using a food processor or crush in a bag with a rolling pin. Combine with melted butter and instant espresso powder; mix until uniformly moistened. Press evenly into the bottom of the prepared pan. Bake for 10 minutes, then allow to cool completely.
03 - In a small bowl, stir together hot espresso, granulated sugar, and coffee liqueur, if using, until sugar is fully dissolved. Set aside to cool to room temperature.
04 - In a large mixing bowl, beat cream cheese, mascarpone, and granulated sugar until smooth and lump-free. Add eggs one at a time, blending thoroughly after each addition. Mix in cooled brewed espresso, vanilla extract, flour, and a pinch of salt until just combined; avoid overmixing.
05 - Brush or drizzle half of the coffee soak evenly over the cooled crust.
06 - Pour the cheesecake batter gently over the soaked crust. Tap the pan on the counter to release any trapped air bubbles.
07 - Place pan in a larger roasting pan and fill roasting pan with hot water halfway up the sides for a water bath. Bake for 60 minutes or until the center barely jiggles when gently shaken. Turn off the oven, crack the door open, and allow cheesecake to cool inside for 1 hour.
08 - Remove cheesecake from the oven and cool at room temperature. Refrigerate for at least 4 hours or overnight for best texture.
09 - In a chilled bowl, whip heavy cream together with powdered sugar and vanilla extract until stiff peaks form.
10 - Release the chilled cheesecake from the springform pan. If desired, brush or drizzle the remaining coffee soak over the top for enhanced flavor.
11 - Spread whipped cream evenly over the cheesecake. Sift a generous layer of unsweetened cocoa powder on top and garnish with chocolate shavings if desired. Slice with a clean knife and serve chilled.