Preheat the oven to 350°F. Grease the bottom of a 10-inch springform pan (3 inches tall).

In a food processor, grind the chocolate cream cookies and melted butter until fine crumbs form. Press the mixture firmly into the bottom of the pan.

Bake for 7-8 minutes, then set aside to cool.

Reduce the oven temperature to 320°F.

In a stand mixer bowl, beat the cream cheese, mascarpone, sugar, salt, and vanilla until creamy.

Lightly whisk the eggs in a separate bowl, then gradually add them to the cream cheese mixture, mixing until just combined.

Add the heavy cream, sour cream, and cornstarch, and mix until smooth.

Wrap the outside of the springform pan tightly with aluminum foil.

Pour half of the cheesecake batter into the crust. Layer the soaked ladyfingers on top, then pour the remaining batter over them.

Place the pan in a larger baking dish filled with 1-2 inches of boiling water.

Bake for about 80 minutes, or until the edges are set but the center is slightly jiggly.

Let the cheesecake cool in the pan for 15 minutes, then transfer to a wire rack to cool completely. Chill in the refrigerator overnight.

In a bowl, whisk together the mascarpone, sugar, and dissolved coffee until creamy.

In a separate bowl, whip the heavy cream until stiff peaks form, then gently fold it into the mascarpone mixture.

Carefully remove the cheesecake from the pan and place it on a serving platter.

Spread a thin layer of the coffee mascarpone cream over the top, then pipe the remaining cream decoratively over the surface.

Dust with cocoa powder before serving.