Prepare the Brownie Base:

Preheat Oven: Preheat your oven to 350°F (175°C). Grease and line an 8x8-inch baking pan with parchment paper, leaving an overhang for easy removal.

Melt the Butter: In a medium saucepan, melt the butter over low heat. Remove from heat and stir in the sugar, followed by the eggs and vanilla extract until well combined.

Add Dry Ingredients: Sift in the cocoa powder, flour, salt, and baking powder. Stir until just combined; do not overmix.

Spread the Brownie Batter: Pour half of the brownie batter into the prepared baking pan, spreading it evenly across the bottom.

Prepare the Cheesecake Layer:

Mix the Cheesecake Filling: In a medium bowl, beat the softened cream cheese and granulated sugar until smooth. Add the egg and vanilla extract, mixing until well combined and creamy.

Layer the Cheesecake: Spread the cheesecake filling over the brownie layer in the baking pan. Drop spoonfuls of the remaining brownie batter over the cheesecake layer. Use a knife or skewer to gently swirl the brownie batter into the cheesecake for a marbled effect.

Bake:

Bake: Bake in the preheated oven for 30-35 minutes, or until the edges are set and a toothpick inserted in the center comes out with a few moist crumbs.

Cool: Remove from the oven and allow to cool in the pan for about 10 minutes. Use the parchment paper overhang to lift the brownies out of the pan and onto a wire rack to cool completely.

Serve:

Slice and Enjoy: Once cooled, slice into squares and serve. Store any leftovers in an airtight container in the refrigerator.