Step 1: Preheat your oven to 350°F (175°C) and grease an 8×8 inch baking pan or line it with parchment paper for easy removal.
Step 2: In a medium bowl, stir together the melted butter, sugar, and vanilla. Add the eggs one at a time, beating well after each addition to ensure a smooth base for your pumpkin chocolate swirl brownies recipe.
Step 3: Divide the butter mixture into two separate bowls. In the first bowl, whisk in the cocoa powder, salt, and 1/4 cup of the flour to create the chocolate batter.
Step 4: In the second bowl, stir in the pumpkin puree, maple syrup, cinnamon, nutmeg, and the remaining 1/4 cup of flour to create the pumpkin batter.
Step 5: Spread about 3/4 of the chocolate batter into the prepared pan. Dollop the pumpkin batter and the remaining chocolate batter over the top in alternating spoonfuls.
Step 6: Use a knife to gently swirl the two batters together to create a marbled effect, being careful not to over-mix.
Step 7: Bake for 30-35 minutes, or until a toothpick inserted into the center comes out with only a few moist crumbs. Let the pumpkin chocolate swirl brownies recipe cool completely in the pan before slicing.