Whisk the flour, baking powder, baking soda, salt, and cinnamon in a large bowl. Set aside. Whisk the oil, eggs, brown sugar, granulated sugar, pumpkin, and vanilla extract together until combined. Pour the wet ingredients into the dry ingredients and use a mixer or whisk until completely combined. The batter will be thick.
2 cups all-purpose flour, 2 teaspoons baking powder, 1 teaspoon baking soda, 1 teaspoon salt, 1 teaspoon cinnamon, 4 large eggs, 1 cup brown sugar, 1/2 cup white sugar, 1 15-ounce can of pumpkin puree or 2 cups homemade mashed pumpkin, 1 teaspoon vanilla extract, 1 cup canola or vegetable oil