Preheat the oven to 325°F and wrap a 9-inch springform pan with two layers of foil on the outside. In a bowl, stir together the almond flour, melted butter, sugar, espresso powder, and salt until evenly combined.
Press the mixture firmly into the bottom of the pan. Bake for 12 minutes until set and fragrant, then remove and let cool.
In a large bowl, beat the cream cheese, mascarpone, and sugar on medium speed until extremely smooth and fluffy, about 4 to 5 minutes. Scrape down the sides and bottom of the bowl several times during mixing to eliminate any lumps.
Dissolve the 2 tsp espresso powder in the Kahlua (or brewed espresso). Add this mixture to the bowl along with the cornstarch and vanilla, and beat on low until well combined.
Add the eggs one at a time, mixing on low speed after each just until incorporated. The batter should be silky and smooth. Do not overmix at this stage.
Pour the filling over the cooled crust. Place the pan inside a roasting pan and carefully add hot water until it reaches halfway up the springform sides. Bake for 55 to 65 minutes, until the cheesecake is set around the edges with a slight wobble in the very center.
Turn off the oven, crack the door open a few inches, and let the cheesecake cool inside for 1 full hour. Remove from the water bath, remove the foil, and refrigerate for at least 6 hours or overnight until completely chilled.
Whip the heavy cream, powdered sugar, and vanilla together until stiff peaks form. Spread the whipped cream in a generous, fluffy layer over the top of the chilled cheesecake.
Dust the entire surface liberally with cocoa powder through a fine mesh sieve, then scatter dark chocolate shavings across the top. Serve cold.