Preheat the oven to 350 degrees F. Spray the bottom of an 8-inch springform pan with non-stick cooking spray or line it with a circle or parchment paper. Set aside.
Add the Oreo crumbs and melted butter to a medium mixing bowl and stir until evenly moistened. Pour the Oreo crumbs into the prepared pan and press firmly around the bottom until an even crust forms. Set aside.
Beat the cream cheese and sugar together in a large mixing bowl with a hand mixer until fluffy. Add the eggs and beat to combine.
With the mixer on low speed, mix in the sour cream, melted chocolate, Kahlúa, espresso, and cornstarch until smooth and evenly combined.
Pour the filling over the Oreo crust. Carefully bang the pan on the counter a few times to release any air bubbles.
Bake for 55 to 60 minutes or until the middle of the cheesecake jiggles very slightly and bounces back when pressed.
Turn off the oven and prop open the oven door. Then allow the cheesecake to rest in the oven for 1 hour. (To avoid cracking, you can carefully run a knife around the rim of the pan after around 10 -15 minutes of resting to loosen the cake from the sides. When the cake shrinks during the cooling process, it won’t stick to the edges and crack.)
Take the cheesecake out of the oven and let it cool down to room temperature. Then cover with plastic wrap and refrigerate for at least 6 hours or overnight. Once chilled, run a knife around the edge of the pan and remove the metal ring around the sides.
When you're ready to serve the cheesecake, beat the heavy cream in a medium mixing bowl with a hand mixer on medium-high speed until it begins to thicken. Sprinkle the sugar in and continue beating until soft peaks form.
Sprinkle the top of the cheesecake with cocoa powder. Then, transfer the whipped cream to a piping bag and pipe swirls around the edge of the cheesecake. Top the whipped cream swirls with chocolate-covered espresso beans if desired.
Notes
Store any leftover cheesecake in an airtight container in the fridge for up to 5 days.