Preheat oven to 350°F (175°C). Grease and line an 8x8 or 9x9-inch baking pan.

In a mixing bowl, whisk melted butter and sugar. Add eggs and vanilla. Stir in cocoa powder, flour, and salt until smooth.

In another bowl, beat cream cheese with sugar, egg, and vanilla until creamy.

Pour most of the brownie batter into the pan. Drop spoonfuls of cream cheese mixture on top, followed by the remaining brownie batter.

Swirl gently with a knife.

Bake for 35–40 minutes or until the center is just set.

Cool completely before slicing.