Preheat your oven to 350°F. Lightly grease a 7x5-inch baking dish and line with parchment paper*.
In a small bowl, whisk together flour, baking powder, baking soda, cinnamon, and salt.
In a medium bowl, whisk together egg, sugar, vegetable oil, and pumpkin puree until very smooth. Whisk in flour mixture. Pour batter into prepared baking dish and bake for 20 to 25 minutes, until a toothpick inserted into the center of the cake comes out with just a few wet crumbs and when gently pressed, the top of the cake springs back.
Cool completely before frosting.