Prepare the brownie mix as directed, bake, and let it cool completely. Cut into ¾-inch cubes and set aside half for the cheesecake.

Preheat the oven to 350°F (175°C). Combine crushed Nilla Wafers, powdered sugar, cocoa powder, and melted butter until the mixture resembles wet sand. Press into a 9-inch springform pan, bake for 8 minutes, and let cool.

Beat softened cream cheese with sugar until smooth and fluffy. Add eggs one at a time, mixing well after each, then stir in vanilla and gently fold in half of the brownie cubes.

Pour the filling over the cooled crust, tap the pan to release air bubbles, drizzle hot fudge in a spiral, and swirl with a knife.

Bake for 50–55 minutes until set but slightly jiggly in the center. Turn off the oven, crack the door, and let it cool for 1 hour.

Cool completely at room temperature, then refrigerate for at least 4 hours or overnight. Run a hot knife along the edge before removing the rim.

Slice and top with extra hot fudge, whipped cream, cherries, or remaining brownie cubes.