Preheat the oven to 350°F / 180°C. Prepare a 13x9 baking pan by spraying with nonstick spray or butter it and add a foil or parchment sling and set it aside.

While the chocolate mixture cools some, start on the cheesecake layer. In a mixing bowl, add 8oz softened cream cheese, 1 cup pumpkin puree, ¼ cup white sugar, 1 ½ teaspoons ground cinnamon, ½ teaspoon pumpkin pie spice, and 1 egg. Using a rubber spatula or a hand mixer (ideally), mix everything together until fully combined and smooth. If using, fold in the mini chocolate chips at this point.

If the chocolate gets a bit thick as it cools, add the ½ cup of oil and it should loosen everything up. In a large mixing bowl, add the chocolate mixture, oil, 2 cups of white sugar, ½ cup of dark brown sugar, 1 teaspoon salt, and 2 teaspoons vanilla extract. Using a whisk or hand mixer, blend everything together. Now add the eggs and egg yolks in, one at a time, mixing until just combined each time. Finally, add the 1 ¾ cups of all-purpose flour a bit at a time and mix until just combined and there’s no obvious streaks of flour. Remove about ¾ of a cup of the brownie batter and reserve it for later.

Add the brownie batter into the prepared 13x9 baking pan and spread it out. The batter will be quite thick, but make sure to spread it from corner to corner and even it out on top.

Now add the pumpkin cheesecake batter on top of the brownie layer, smoothing it out as well. Add the remaining brownie batter in dollops over top of the cheesecake layer. If the batter is too thick, try microwaving it for a bit just to loosen it up. Using a knife or toothpick or chopstick, create swirls back and forth through the brownie and cheesecake layers to create a marbled pattern. Try not to go all the way through to the brownie layer on the bottom.

Place the brownies into the center rack of the oven and bake for 40-50 minutes. Use a toothpick or cake tester to check for doneness. Check the cheesecake parts as they tend to take longer than the base, once it’s mostly clean with a few crumbs, remove from the oven.

Allow the brownies to cool in the pan until they’ve had time to set and then you can use the sling to remove them while only a little warm. Let the brownies finish cooling to room temperature before slicing.