Preheat your oven to 350°F and line an 8x8-inch baking pan with parchment paper, leaving some overhang for easy removal.
In a large bowl, beat the cream cheese until smooth and creamy.
Add the pumpkin puree, sugar, egg, vanilla, salt, pumpkin pie spice, and cinnamon. Mix until everything is well combined and smooth.
In another bowl, make the brownie batter according to the instructions on the box. Stir in three-quarters of the chopped dark chocolate to add richness.
Spread three-quarters of the brownie batter into the prepared pan. Dollop spoonfuls of the pumpkin mixture and the rest of the brownie batter over the top, alternating as you go.
Take a butter knife and gently swirl the two batters together to create a marbled effect.
Sprinkle the remaining chopped chocolate evenly on top.
Bake for 45–50 minutes, or until the edges are firm and a toothpick inserted in the center comes out mostly clean. Let cool completely in the pan before slicing. Enjoy!