Preheat the oven to 350°F (175°C).
Prepare a muffin tin by greasing it or using cupcake liners.
In a bowl, mix melted butter and granulated sugar until well combined.
Add in the eggs and vanilla extract, mixing until incorporated.
Sift together cocoa powder, flour, and salt before folding them into the wet mixture.
Divide the brownie batter evenly among the muffin cups.
In a separate bowl, beat the cream cheese until smooth, then mix in powdered sugar and sour cream.
Spoon the cheesecake mixture over the brownie layer in each cup.
Bake in the preheated oven for 25-30 minutes or until the tops are set.
Allow to cool, then refrigerate for at least 2 hours before serving.
Top with assorted toppings before serving.
