1. Prepare the Crust:

• Preheat oven to 350°F (175°C).
• In a small bowl, combine the chocolate cookie crumbs, melted butter, and optional sugar. Stir until evenly moistened.
• Press the crumb mixture firmly and evenly onto the bottom and slightly up the sides of the 9-inch springform pan.
• Bake for 8-10 minutes. Let cool completely on a wire rack while you prepare the filling.

2. Prepare the Cheesecake Filling:

• Reduce oven temperature to 325°F (160°C).
• In a large bowl, beat the softened cream cheese with an electric mixer on medium speed until completely smooth and free of lumps.
• Gradually beat in the granulated sugar until smooth.
• Add the eggs one at a time, beating lightly on low speed just until each egg is incorporated. Do not overmix.
• Stir in the sour cream (or heavy cream) and vanilla extract.
• Gently fold in the melted and slightly cooled chocolate until just combined. Don’t overmix.
• Pour the filling evenly over the cooled crust.

3. Bake the Cheesecake (Water Bath Recommended):

• Optional Water Bath: Wrap the outside of the springform pan tightly with 2-3 layers of heavy-duty aluminum foil to prevent water leakage. Place the wrapped pan in a larger roasting pan. Carefully pour hot water into the roasting pan until it reaches about halfway up the sides of the springform pan.
• Carefully transfer the pan (or roasting pan with water bath) to the preheated oven.
• Bake for 60-75 minutes, or until the edges of the cheesecake are set and the center is still slightly jiggly when gently shaken.
• Turn off the oven and let the cheesecake cool in the oven with the door slightly ajar for 1 hour. This helps prevent cracking.
• Remove the cheesecake from the oven (and water bath, if used). Remove the foil. Let it cool completely on a wire rack at room temperature.

4. Chill the Cheesecake:

• Once completely cool, cover the cheesecake loosely with plastic wrap and refrigerate for at least 6 hours, or preferably overnight, until firm.

5. Prepare the Cherry Topping:

• While the cheesecake chills or before serving: In a medium saucepan, combine the cherries, sugar, and water/cherry juice.
• In a small bowl, whisk the cornstarch with 2 tablespoons of cold water until smooth to create a slurry.
• Bring the cherry mixture to a simmer over medium heat. Stir in the cornstarch slurry.
• Cook, stirring constantly, until the mixture thickens and bubbles, about 2-3 minutes.
• Remove from heat. Stir in the lemon juice and Kirsch (or almond extract), if using.
• Let the topping cool completely before using. It will thicken further as it cools.

6. Garnish and Serve:

• Carefully run a thin knife around the edge of the chilled cheesecake before releasing the sides of the springform pan.
• Spoon the cooled cherry topping over the top of the cheesecake, spreading it gently.
• In a chilled bowl, whip the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.
• Pipe or dollop the whipped cream around the edges of the cheesecake.
• Sprinkle generously with chocolate shavings or curls. Garnish with fresh cherries, if desired.
• Slice with a sharp knife dipped in hot water and wiped clean between cuts for neat slices.