Preheat your oven to 350°F (175°C). Grease and flour an 8×8 inch baking pan or line it with parchment paper.

In a large mixing bowl, whisk together the melted butter and granulated sugar until well combined. Stir in the vanilla extract.

In a separate bowl, whisk together the cocoa powder, baking powder, and salt. Gradually add this mixture to the wet ingredients and stir until just combined.

Add the eggs one at a time, beating well after each addition until smooth and glossy.

If using, gently fold in the gluten-free chocolate chips.

In another bowl, beat the softened cream cheese with 1/3 cup granulated sugar until smooth. Mix in the egg yolk and 1 teaspoon vanilla extract until incorporated.

Pour about two-thirds of the brownie batter into the prepared pan, spreading it evenly.

Dollop spoonfuls of the cream cheese mixture on top, then cover with the remaining brownie batter.

With a toothpick or thin knife, gently swirl the cream cheese into the brownie batter.

Bake for 30-35 minutes until a toothpick inserted in the center comes out with moist crumbs.

Let them cool completely in the pan on a wire rack before lifting out and cutting into squares.