Crust

1. Preheat oven to 325°F (160°C) and lightly grease a 9-inch (23 cm) springform pan.
2. In a small bowl combine the finely crushed Oreos and melted butter. Mix until completely coated. Firmly press the mixture into the bottom of the pan and slightly up the sides to form an even crust.
3. Bake for 10 minutes, then remove and let cool before adding the filling.

Cheesecake Filling

1. Prepare the ganache. Place the chocolate in a heatproof mixing bowl. Place the heavy cream in a small saucepan over medium heat. Cook until the mixture begins to simmer. Pour the cream over the chocolate, cover with plastic wrap and set aside for 3 minutes. Whisk the mixture until smooth, cover with plastic wrap and set aside.
2. Beat the cream cheese with an electric mixer on medium-low speed for several minutes until completely smooth. Scrape down the sides and bottom of the bowl as needed.
3. In a small bowl, rub the orange zest into the granulated sugar with your fingertips to help release and intensify the orange flavor. Add the orange zest, sugar, cocoa powder and salt to the cream cheese. Continue beating until smooth.
4. Add the sour cream, vanilla extract and orange juice. Continue mixing until well combined.
5. Add the eggs one at a time, beating after each addition until just combined. Don’t overmix here!
6. Fold the chocolate ganache into the cheesecake batter until fully incorporated.
7. Pour the cheesecake batter into the cooled crust.
8. With the oven still at 325°F (160°C), place the cheesecake on the center rack. To safeguard against any leakage, you can also place the cheesecake on a foil-lined pan. Bake for 30 minutes.
9. Reduce heat to 250°F (120°C). Slightly crack the oven door for the first several minutes to help the oven cool more quickly. Bake for 35-40 minutes or until the internal temperature of the cheesecake reaches 145°F (63°F) with an instant read thermometer. The edges will be mostly set, but the center will still be quite wobbly.
10. Turn off the oven and crack the oven door 2 inches (5 cm). Let the cheesecake sit in the warm oven for another 30 minutes.
11. Remove the cheesecake from the oven and allow to cool at room temperature for 2 hours. Transfer to the refrigerator for at least 6 hours before releasing from the springform pan and adding the ganache.

Toppings

1. Place the chocolate pieces in a heatproof bowl.
2. Heat the heavy cream in a small saucepan over medium heat until it begins to simmer. Immediately pour the heavy cream over the chocolate, cover and let sit for 3 minutes.
3. Whisk the mixture until smooth. Pour the ganache onto the cheesecake and spread the mixture evenly over the top.
4. Once the ganache has set, decorate with candied oranges.