Step 1

Preheat oven to 350 degrees. Line a 9 x 13 rectangular baking pan or dish with parchment paper or grease with cooking spray.

Step 2

Place the chocolate and the butter inside a heat-proof bowl. Fill a small saucepan halfway with water and bring it to a simmer over medium heat. Set a heatproof bowl over the saucepan melt the chocolate and butter while stirring occasionally until melted and smooth. Turn off the heat.

Step 3

In a large bowl, whisk together flour, baking powder, and salt; set aside.

Step 4

Using a hand mixer in a large bowl or stand mixer, mix the sugar, eggs, and vanilla, on medium speed until fluffy and combined, about 3 to 5 minutes.

Step 5

Slowly add the flour mixture to the wet ingredients and mix to combine, stopping periodically to scrape the sides of the bowl.

Step 6

Divide the batter between 2 medium bowls (about 2 cups per bowl). Add the chocolate mixture to one bowl and stir to combine.

Step 7

To the non-chocolate mixture, add the pumpkin, oil, cinnamon, and nutmeg and stir to combine.

Step 8

Pour the chocolate batter into the prepared pan and smooth the top with a rubber spatula. Next, pour the pumpkin batter over the chocolate in a semi-swirl way. With a small spatula gently swirl the two batters to create a marbled effect.

Step 9

Bake for 35 to 40 minutes or until set and a toothpick comes out clean when inserted in the center of the pan.

Step 10

Remove from the oven and allow the brownies to cool on a wire rack before cutting into 16 squares.