Preheat the oven to 350 degrees F.
Add the Oreos to a large food processor and pulse until it resembles fine crumbs.
Add the melted butter and pulse until evenly distributed.
Wrap a 9" springform pan around the bottom with aluminum foil
Press the Oreo crust mixture into the springform, about 2" up the sides.
Bake in the preheated oven for 10 minutes.
While the crust is baking, prepare the cheesecake filling.
Add the cream cheese to a large mixing bowl and beat for 2 minutes, until light and fluffy.
Add the sugar, cocoa powder, vanilla, and salt, beating until well combined.
Add the eggs one at a time, beating until combined, and scraping down the sides of the bowl between each addition.
Add the heavy cream and beat until combined.
Finally, add the melted semisweet chocolate, scraping down the sides to ensure it is all evenly combined.
Spread cheesecake filling on top of baked crust.
Reduce oven temperature to 325 degrees F.
Place a large roasting pan on one rack in the oven.
Place the springform pan into the roasting pan.
Pour enough water into the roasting pan to come up about 2" on the springform pan sides.
Bake in the preheated oven for 1 hour. The cheesecake will still appear jiggly in the middle, but it will set up as it cools.
Let the cheesecake cool at room temperature for about 30 minutes and then refrigerate for at least 4 hours - preferably overnight.