Preheat and Prep: Preheat oven to 350°F (175°C). Line a 9×13 inch baking pan with parchment paper, leaving an overhang.
Make Brownie Batter: In a large bowl, whisk together melted butter and 2 cups sugar. Whisk in 4 eggs and 1 teaspoon vanilla. Stir in flour, cocoa powder, and salt until just combined. Spread two-thirds of the brownie batter evenly into the prepared pan. Reserve the remaining batter.
Make Cream Cheese Filling: In a medium bowl, beat softened cream cheese and ½ cup sugar until smooth. Beat in 1 egg and 1 teaspoon vanilla. Pour this mixture over the brownie base.
Make Pumpkin Swirl: In a small bowl, mix pumpkin puree, pumpkin pie spice, and 1 tablespoon sugar. Drop spoonfuls of this mixture over the cream cheese layer.
Add Remaining Brownie: Drop spoonfuls of the reserved brownie batter over the pumpkin mixture. Gently use a knife or skewer to swirl the layers together for a marbled effect.
Bake: Bake for 35-40 minutes, or until the edges are set and a toothpick inserted near the center comes out with moist crumbs (not wet batter).
Cool: Let cool completely in the pan before lifting out and cutting into squares.
