Preheat your oven to 175°C (350°F) and line a square baking pan with parchment paper.
Melt the dark chocolate and butter together in a heatproof bowl until smooth, then let it cool slightly.
In a large bowl, whisk together the eggs, granulated sugar, and brown sugar until well combined.
Fold the melted chocolate mixture into the egg and sugar base.
Sift in the cocoa powder, flour, and salt, mixing until just combined; do not over-mix.
In a separate bowl, beat the cream cheese with powdered sugar and pumpkin pie spice until smooth, then fold in the pumpkin puree.
Pour half of the brownie batter into the prepared pan.
Spread the pumpkin cheesecake mixture evenly over the batter, then top with the remaining brownie batter.
Use a knife to gently swirl the layers to create a marbled look.
Bake for 35 to 40 minutes or until a toothpick inserted into the center comes out with a few moist crumbs.
Allow the brownies to cool completely in the pan before slicing for clean, professional edges.