Chocolate crust:

• Preheat oven to 350F (conventional) and butter the bottom of a 10" springform pan (3" tall)
• Grind the chocolate creme cookies and melted butter in a food processor until they form a fine crumb. Transfer to the pan, and pack very tightly using a measuring cup. You can push a little up the edges but keep most on the bottom.
• Bake for 7-8 min

Cheesecake filling:

• Adjust the oven temperature to 320F (conventional)
• Add the cream cheese and mascarpone cheese to the bowl of your stand mixer along with the sugar, vanilla and salt. Use the paddle attachment to beat for 2-3 minutes on medium-low speed until creamy. Keep scraping the sides of the bowl to ensure everything combines evenly
• Break your eggs in a separate bowl and whisk lightly. Don’t overbeat because if the eggs get airy they will give a spongy texture to the cheesecake. Add them to the batter slowly and mix at a low speed until JUST combined
• Add the cream, sour cream, and cornstarch (sifted), and mix at low speed until just combined. Keep scraping sides of the bowl

Assembly & baking:

• Seal your pan tightly with aluminum foil on the outside (not on the top)
• Pour half of the batter into the crust and gently shake to spread it. Tap the pan a few times on the counter to get rid of any air bubbles
• Soak the ladyfingers in the coffee quickly (just a quick dip on each side, don't hold them in), and layer in the cheesecake pan gently. Try to get them as close as possible, and cut some ladyfingers into smaller pieces to fill in the gaps
• Gently add the remaining cheesecake batter (you can fill the pan until just under the brim) and lightly shake and tap again
• Place a large tray in your oven and fill it with 1-2 inches of boiling water. Place the springform pan in the water and bake for about ~80 min. Don’t open the oven until at least 75 minutes in. When done, the cheesecake should have firm edges but a jiggly center
• Remove from the oven, and cool at room temp for 15 min. Then run a butter knife between the cheesecake and the walls of the pan to separate them (don't open the pan), and cool for 2-3 hours at room temp. After this, place in the fridge and chill overnight (no cover needed)

Coffee mascarpone cream:

• The next day, add the mascarpone, sugar and coffee to a bowl, and whisk until creamy. Then add the heavy cream, and whisk on low speed until the mixture forms stiff peaks

Decoration & serving:

• Carefully remove the chilled cheesecake from the pan and transfer to a serving stand
• Spread on a thin layer of the coffee mascarpone cream. Transfer the remaining to a piping bag and pipe it on top of the cheesecake using any pattern you like
• Dust the cheesecake with cocoa powder, and you're ready to enjoy!