Preheat oven to 350F
Line loaf pan (preferably 8.5“ x 4.5” x 4“ or so) with parchment paper and spray liberally with oil spray or coat well with oil
In a medium-sized bowl sift together the gluten-free flour, cornstarch, baking soda, baking powder, and spices
In a separate large mixing bowl combine the room temperature large eggs, light brown sugar, white sugar, and vanilla extract and whisk together
Add the oil and pumpkin puree and whisk until smooth and mix until smooth
Add dry ingredients to wet ingredients and stir well to combine. Allow to sit for 20-30 minutes for the flour to fully hydrate
Transfer the pumpkin bread batter to the prepared loaf pan. Use a spatula, spoon, or small offset to smooth it out evenly
Bake for 55-65 minutes. The loaf is done when it is golden brown and a toothpick or cake tester inserted in the center comes out clean
Allow for it to cool in the pan for 10 minutes. Then remove it from the loaf pan, transfer it to a cooling rack and allow it to cool completely