Preheat your oven to 350°F (175°C) and grease an 8x8 inch baking pan or line it with parchment paper for easy removal.

In a large mixing bowl, combine the melted butter and 1 cup of granulated sugar. Whisk well until the mixture is smooth.

Beat in the 2 large eggs and vanilla extract until fully incorporated.

Sift in the cocoa powder, flour, salt, and baking powder. Stir gently with a spatula until just combined; do not overmix.

Pour approximately two-thirds of the chocolate brownie batter into the prepared baking pan and spread it into an even layer.

In a separate medium bowl, beat the softened cream cheese, 1/4 cup sugar, and egg yolk until the mixture is smooth and creamy.

Drop spoonfuls of the cream cheese mixture randomly over the brownie base, then drop the remaining brownie batter in the empty spaces.

Take a butter knife or a skewer and gently swirl the two batters together to create a marbled effect.

Press the fresh raspberries gently into the top of the batter, distributing them evenly.

Bake for 30 to 35 minutes, or until the edges are set and a toothpick inserted into the brownie portion comes out with just a few moist crumbs.

Allow the brownies to cool completely in the pan before slicing into squares to ensure clean cuts.