In a large bowl, add the eggs, oil, water, and vanilla extract. Whisk well to combine. Set aside.

In a separate bowl, add the granulated sugar, 3/4 cup of flour, powdered sugar, and salt. Mix to combine.

Pour the dry ingredients into the wet and mix until combined. Separate the batter in half by pouring half of the batter into another bowl.

In one bowl, add the cocoa powder and chopped chocolate (reserve some to add to the tops of the bars). Mix until just combined.

In the other bowl, add the pumpkin puree, pumpkin pie spice, and remaining 2 tablespoons of flour. Mix until combined.

Pour the chocolate layer into the baking dish. Use a spatula or your hands to spread it evenly and smooth it out - it will be very thick! Add the pumpkin layer on top, using a spatula to spread it evenly and smooth it out. Add the remaining chopped chocolate on top.

Bake in the preheated for 40-45 minutes, or until a knife inserted in the center comes out just clean. The brownies will continue to bake slightly as they cool, so it’s better to underbake them than to overbake.

Let the brownies cool completely and then cut into 9 squares.