01 - Preheat the oven to 350°F. Line a 12-cup muffin tin with paper liners or grease thoroughly with cooking spray.
02 - Melt butter in a medium microwave-safe bowl. Whisk in granulated sugar and brown sugar until mixture appears glossy and smooth. Add eggs and vanilla extract, mixing until fully incorporated.
03 - Sift cocoa powder, flour, and salt directly into the wet mixture. Fold gently with a spatula until just combined, being careful not to overmix the batter.
04 - Distribute brownie batter evenly among the 12 muffin cups, using approximately 1 heaping tablespoon per cup. Tap the pan gently on the counter to settle the batter.
05 - In a separate bowl, beat softened cream cheese with an electric mixer until completely smooth. Add sugar, egg, and vanilla extract, continuing to beat until creamy and free of lumps.
06 - Soon approximately 1 tablespoon of cheesecake filling over each brownie base. Use the back of the spoon to gently smooth the tops, creating an even layer.
07 - Generously sprinkle each cup with your selected toppings—mini chocolate chips, chopped nuts, crushed Oreos, and mini M&Ms. Press toppings lightly into the cheesecake layer to ensure they adhere.
08 - Bake for 22 to 25 minutes. The cheesecake should be set and the edges of the brownie cups firm, while the center may still have a slight jiggle.
09 - Let the cups cool in the muffin tin for 10 minutes before carefully transferring to a wire rack. Refrigerate for at least 1 hour before serving to achieve optimal texture and flavor.