Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking pan.
In a large mixing bowl, combine the melted butter, granulated sugar, and 1 teaspoon of vanilla extract. Mix until well combined.
Add the eggs one at a time, mixing well after each addition.
In another bowl, whisk together the flour, cocoa powder, and salt.
Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Pour half of the brownie batter into the prepared baking pan and spread it evenly.
In a separate bowl, beat the softened cream cheese, powdered sugar, and 1 teaspoon of vanilla extract until smooth.
Spread the cream cheese mixture over the brownie layer in the pan.
Spoon the remaining brownie batter on top and gently swirl it with a knife to create a marbled effect.
Bake for 30-35 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Allow the brownies to cool in the pan before cutting into squares.