Preheat oven to 350°F and prepare 9 inch springform pan with cooking spray
Melt the stick of butter in a microwave safe bowl or glass in 30 second increments until the butter is fully melted. In my experience, it took (2) 30 second intervals to melt the butter, stirring in between. Pour the melted butter into a medium mixing bowl. Next, stir in the granulated sugar and mix for 2-3 minutes by using an electric or stand mixer. Mix until the butter and sugar are fully combined.
Slowly mix in the eggs, one at a time. Make sure each egg is fully incorporated before moving on to the next one. Then mix in the vanilla extract and salt
Add in the flour and cocoa powder and mix until well-combined. Make sure the batter has a smooth consistency without any lumps. Carefully fold in the chocolate chips and make sure they are spread evenly throughout the batter.
Pour the batter into the prepared 9″ springform pan and ensure it is spread evenly along the bottom.
Bake for 20 minutes at 350°F or until a toothpick inserted into the center comes out clean.
Allow the brownie layer to cool while you are making the cheesecake layer.
Cheesecake Filling
In a large bowl, beat the cream cheese and sugar with an electric or stand mixer until smooth and creamy.
Add in the eggs, one at a time. Make sure each egg is fully incorporated before adding in the next.
Stir in the vanilla extract, sour cream, and heavy cream. Mix until well combined.
Combining & Finishing the Brownie Cheesecake
Pour the cheesecake batter over the brownie layer. Use a spatula to make sure that the top is smooth and level.
Bake at 350°F for 40-45 minutes or until the cheesecake is set, but the center is still slightly jiggly.
Turn off the oven and leave the cheesecake inside with the oven door slightly open (around 2″) for around 15 minutes.
Remove the cheesecake from the oven and run a knife around the edge of the springform pan to loosen it.
Allow the cheesecake to cool for another 10 minutes, then cover and refrigerate for at least 4 hours. I recommend leaving in the fridge overnight.
Remove the cheesecake from the fridge and remove the springform ring.
Slice the cheesecake into pieces and add the optional whipped cream topping.