• Preheat the oven to 325 F (160 C) degrees.
• Wrap the outside of a 9-inch (23-cm) springform pan with tin foil. Wrap the pan at least 3 times to ensure that

Oreo Crust

• Crush the cookies (wafers and filling) in a food processor until fine crumbs. Or place in a freezer bag and crush with a rolling pin.
• Mix the cookie crumbs with the melted butter.
• Press the mixture into the bottom of springform pan, creating a slight lip around the edges.
• Bake in the preheated oven for 8 minutes. Remove from the oven and keep the oven turned on.

Cheesecake Filling

• Chop the chocolate into very fine pieces and place in a heatproof bowl. Microwave for 30-second intervals at medium power (not high power, which is often standard). Stir between each interval until smooth. Set aside.
• In a very large bowl beat the cream cheese and sugar until smooth.
• Beat in the melted chocolate. Turn off the mixer and scrape down the sides and bottom of the bowl.
• Whisk together the cocoa and water in a small cup.
• Beat the dissolved cocoa and sour cream into the batter.
• Mix in the eggs 1 at a time. Stop mixing as soon as the batter is smooth.

Baking and Cooling

• Place the springform pan (still wrapped in tin foil) in the middle of a large roasting pan.
• Pour the cheesecake filling over the crust and smooth the top.
• Pour hot water into the roasting pan so that there's about ½ - 1 inch (1-2 cm) of water in the pan.
• Place the roasting pan with the cheesecake inside in the oven. Bake for 55-65 minutes, or until the top looks just set. It should still wobble in the middle if you gently nudge the pan.
• Remove from the oven. Cool the cheesecake in the roasting pan until the water is room temperature, then remove the springform pan from the roasting pan and continue cooling on a wire rack. (Do not unclamp the outer ring of the springform pan).
• Once the pan is room temperature to the touch, cover with foil and place in the fridge to chill for at least 6 hours or overnight.

Topping & Serving

• Pit the cherries and slice in half.
• Add the cherries, sugar and lemon juice to a medium saucepan over low heat. Gently stir the mixture as the cherries soften and the juices begin to come out.
• Dissolve the cornstarch in the water, then add to the cherries and stir. The cherry mixture will start to thicken. Remove from the heat
• Beat the whipping cream and powdered sugar until peaks form.
• Transfer the whipping cream to a piping bag (I used a 1M Wilton tip).
• Remove the cheesecake from the fridge. Trace around the outer edge with a sharp knife, then unclamp the outer ring of the pan.
• Pipe rosettes around the edges of the cheesecake. Carefully spoon the cherry topping in the middle. Optionally, add a few chocolate shavings over the whipped cream.
• Slice with a thin, sharp knife. Be sure to slice all the way through the crust.