Preheat oven to 350 degrees (176 celsius).

Grease and flour a 9 x 13 inch baking pan.

In a large bowl, mix together pumpkin, vegetable oil, eggs, and sugar using an electric mixer until well combined.

In the same bowl, add flour, baking soda, baking powder, cinnamon, and salt.

Stir until all ingredients are fully incorporated.

Pour the brownie batter into the prepared baking pan, spreading evenly.

Bake in the preheated oven for 30 minutes, or until a toothpick inserted into the center comes out clean or with moist crumbs.

Let the brownies cool completely in the pan before cutting into squares.

Serve with whipped topping or frost with a cream cheese frosting, if desired.

Garnish with candied corn or sprinkle with nuts if desired.