• Heat the oven to 300°F. Grease the bottom and sides of a 9-inch springform pan.

Make the crust:

• In a small 1.5-qt mixing bowl, combine cookie crumbs, melted butter and brown sugar.
• Press the crumb mixture halfway up the sides and firmly across the bottom of the springform pan to create a dense, even crust. Place the springform in the freezer to chill while you prepare the filling.

Make the filling:

• In a large bowl, add cream cheese, mascarpone, granulated sugar, heavy cream, espresso powder, vanilla extract and cornstarch. Mix on low speed with a hand mixer until smooth.
• In a separate bowl lightly beat the eggs and egg yolk, then stir them into the cheesecake batter by hand.
• Transfer the batter to the prepared crust and smooth the top.
• Wrap the outside of the springform pan tightly in two layers of heavy-duty aluminum foil, covering both the bottom and sides (this helps prevent water from seeping in).
• Place the wrapped springform pan into a larger roasting pan and pour in about 1 to 2 inches of boiling water.
• Carefully transfer the entire pan assembly to the oven and bake for 55-60 minutes, or until instant-read thermometer inserted into the center registers 155°F. The center should jiggle slightly, while the edges appear set. The cheesecake will continue to firm up as it cools.
• Turn off the oven, leave the cheesecake inside, and prop the oven door open a couple of inches with a wooden spoon or other kitchen utensil. Let the cheesecake rest in the oven for 1 hour before removing.
• Run a sharp knife, around the inside edge of the pan, then release the springform ring.
• Refrigerate for at 3 hours before slicing.
• If desired, dust the top with cocoa powder and/or my stabilized Chantilly whipped cream.