Preheat the oven to 350 F. Prep a 9 inch springform pan with parchment, then spray lightly with baking spray.
In a food processor, pulse the oreos until they are fine crumbs. Add the butter and pulse until evenly combined.
30 oreos, 6 tablespoon butter
Press the crust firmly into the prepared pan about 1.5-2 inches up the side. Bake for 8-10 minutes, then set aside to cool.
Reduce the oven temperature to 325°F and position two racks—one in the middle and one on the lowest level. Start heating 3 cups of water in the microwave; you’ll need it when the cheesecake goes into the oven.
In a medium mixing bowl, microwave the water, espresso powder, and chocolate, stirring well every 30 seconds until the mixture is completely smooth. Set aside to cool.
¼ cup hot water, ¼ teaspoon espresso powder, 10 oz dark or bittersweet chocolate
In a large mixing bowl or the bowl of a stand mixer fitted with a paddle attachment, beat the cream cheese, sugar, salt, and vanilla on medium-high until smooth, about 2 minutes, scraping 1-2 times. The mixture should be very smooth.
24 oz cream cheese, 1 cup granulated sugar, ½ teaspoon salt, 1 teaspoon vanilla
Add the sour cream and eggs one at a time and mix on low, beating until each is well combined before adding the next one. Scrape the bowl occasionally.
¼ cup sour cream, 4 eggs
Add the flour mixture and mix on low until just combined.
3 tablespoon flour
Pour in the chocolate mixture and combine on low until just combined, scraping well.
Place a cookie sheet with cheesecake on middle rack. Place roasting pan or 9x13 pan on bottom rack and pour in the hot water.
Bake at 325 for 55 minutes. Then turn the oven off and prop the oven door slightly (I used a wooden spoon) and allow to cool for 1 hour. Don't open the oven all the way or the heat will escape.
Remove from oven and cool 3-4 hours at room temperature, then refrigerate overnight or until fully chilled.
Once fully cold, remove from the pan. Then make the ganache.
Microwave the heavy cream in a microwave safe bowl for 45-60 seconds until very hot, but not quite boiling. Pour the hot cream over the chocolate, cover with a plate, and let sit without stirring for 3 minutes. Then stir well until the mixture is smooth.
⅓ cup heavy cream, ⅓ cup bittersweet or semisweet chocolate chips
Pour the ganache into the center of the cooled cheesecake and use an offset spatula to spread it to the edges. You can serve immediately or allow the ganache to set for 30-60 minutes first.