Preheat your oven to 350°F (175°C) and grease a 9x9 inch baking pan with butter or non-stick spray.

In a large mixing bowl, whisk together the melted unsalted butter and granulated sugar until well combined and glossy, about 1 minute.

Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

Gently fold in the all-purpose flour, cocoa powder, and salt until just combined, creating a thick and fudgy brownie batter.

In a separate bowl, beat the softened cream cheese using an electric mixer until smooth and creamy, approximately 2 minutes.

Gradually add the sugar, egg, and vanilla extract, mixing until velvety and well-blended.

Pour the prepared brownie batter evenly into the greased baking pan, smoothing it out to create a uniform base.

Dollop spoonfuls of the cheesecake mixture on top of the brownie batter and swirl gently with a knife.

Place the pan in the preheated oven and bake for 30-35 minutes.

Allow the brownies to cool in the pan on a wire rack for at least 30 minutes before cutting into squares.