1. Preheat your oven to 350°F (175°C) and line a 9×13-inch baking pan with parchment paper, leaving a bit of overhang for easy removal.
2. In a large bowl, whisk together the melted butter and 2 cups of granulated sugar until well combined.
3. Add the vanilla extract and eggs, one at a time, mixing thoroughly after each addition.
4. In a separate bowl, sift together the flour, cocoa powder, and salt. Gradually incorporate the dry ingredients into the wet mixture, stirring until smooth.
5. Pour the brownie batter into the prepared pan, smoothing the top with a spatula.
6. In another bowl, beat the softened cream cheese until creamy. Add the pumpkin puree, 1/4 cup of granulated sugar, cinnamon, nutmeg, and ginger, mixing until smooth.
7. Spoon the pumpkin cheesecake mixture over the brownie batter in dollops, then use a knife to swirl the two layers together for a marbled effect.
8. Bake for 40-45 minutes, or until a toothpick inserted into the center comes out mostly clean with a few moist crumbs. Avoid overbaking to keep the bars fudgy.
9. Allow the bars to cool completely in the pan before using the parchment overhang to lift them out. Cut into squares and serve.

From my experience, the key is patience—letting the bars cool completely ensures that each slice is perfectly set and easy to handle.