Preheat your oven to 325°F (163°C). Line the bottom of a 9-inch springform pan with parchment paper and grease the sides with butter.

In a microwave-safe bowl, melt unsalted butter until smooth, about 30-45 seconds. Stir in granulated sugar, then add eggs one at a time, mixing thoroughly.

Sift in cocoa powder, all-purpose flour, salt, and vanilla extract, stirring until the brownie batter is smooth and glossy.

Pour the brownie batter into the prepared springform pan and spread evenly. Bake for 18–20 minutes.

Allow the brownie to cool slightly, then beat softened cream cheese with granulated sugar until smooth. Add sour cream, eggs, and vanilla extract, mixing until incorporated.

Carefully pour the cheesecake filling over the cooled brownie base.

Bake at 325°F for 45–50 minutes until the center is set but slightly jiggles.

Turn off the oven, crack the door open, and let the cheesecake cool gradually for about 1 hour.

Refrigerate the cheesecake for at least 4 hours or overnight.

To prepare the ganache, heat heavy cream in a saucepan until simmering. Pour over chocolate chips and let sit for 2 minutes. Stir until smooth.

Pour ganache over the chilled cheesecake and slice before serving.