Preheat the oven to 350°F (175°C).
In a medium saucepan, melt the butter over low heat. Remove from heat and stir in both sugars until well combined.
Add the eggs, one at a time, mixing well after each addition. Stir in the vanilla extract.
Sift together the flour, cocoa powder, and salt, then fold into the wet mixture until just combined.
Grease a muffin tin and pour brownie batter evenly into each cup, about halfway full.
In a bowl, mix softened cream cheese, powdered sugar, and sour cream until smooth. Spoon the cheesecake filling over the brownie batter in each cup.
Sprinkle chocolate chips on top of each cheesecake filling.
Bake in the preheated oven for 20-25 minutes, or until the brownie layer is set.
Let the brownie cheesecake cups cool slightly in the tin before transferring them to a wire rack.
Once fully cooled, garnish with whipped cream before serving.