Preheat your oven to 350°F (175°C) and line an 8×8 inch baking dish with parchment paper.
In a medium bowl, whisk together the melted butter and 1 cup of sugar until well combined.
Add 2 eggs and vanilla, beating the mixture until smooth.
Fold in the flour, cocoa powder, and salt until just combined, then spread the brownie base evenly into the baking dish.
In a separate bowl, cream together the softened cream cheese and 1/4 cup sugar until smooth.
Add the egg yolk, pumpkin puree, and pumpkin pie spice to the cream cheese mixture and mix thoroughly.
Drop spoonfuls of the pumpkin mixture over the brownie batter.
Use a butter knife or toothpick to gently swirl the mixtures to create a marble effect.
Bake for 30–35 minutes until the edges are set and a toothpick inserted into the brownie portion comes out with just a few moist crumbs.
Remove from the oven and let cool completely on a wire rack before cutting into 16 squares.