Make the Crumb Crust: In a medium bowl, whisk together the Oreo crumbs, sugar, and salt. Add the melted butter and stir with a fork until evenly moistened. Press into the bottom and up sides of the prepared springform pan. Refrigerate while you prepare the filling.
Make the Cheesecake: Using an electric mixer on medium-low speed, beat the cream cheese, sugar, flour and salt until the mixture is creamy and no lumps of cream cheese remain, about 3 minutes. Scrape down the sides of the bowl, add the heavy cream and vanilla and beat to combine. Beat in the eggs and yolk one at a time, beating for about 15 seconds before adding the next. Using a rubber spatula, mix a few times by hand to ensure that all of the ingredients are evenly incorporated. Gently fold in the cubed brownies.
Pour the filling into the chilled crust and spread into an even layer. Place the springform pan on a rimmed baking sheet. Bake until the outer couple inches of cheesecake looks puffed and set, but the center still jiggles when you move the pan, about 40 to 55 minutes. Turn off the oven, crack open the door and leave the cheesecake inside for 1 hour.
After an hour, remove the cheesecake from the oven, place on a wire cooling rack and run a thin knife around the edge of the cake. Allow to cool completely to room temperature. Once the cheesecake has cooled to room temperature, refrigerate for at least 4 hours, preferably overnight.
Make the Chocolate Ganache: Place the chocolate in a 4-cup measuring cup; set aside. Place the cream in a small saucepan over medium heat and warm until it just comes to a boil. Pour the cream over the chopped chocolate and let sit for 2 minutes. Begin whisking the mixture in the center, gradually working your way outward until the ganache is completely smooth. The ganache should be slightly thickened, yet still a pourable consistency. If it is still too thin, let sit at room temperature, stirring occasionally, until it reaches the correct consistency.
Pour the ganache evenly over the top of the cheesecake. If it's a little thinner, it will likely spread out on its own; if it is thicker, you may need to use an offset spatula to spread it into an even layer. Refrigerate for at least 30 minutes to allow the ganache to set.
When ready to serve, unmold the cheesecake and place it on a serving platter. Leftover cheesecake can be stored, covered, in the refrigerator for up to 1 week. It can also be frozen (whole or in slices) for up to 2 months.