In a bowl, mix together gluten-free flour, cornstarch, salt, baking soda, baking powder, cinnamon, ginger, nutmeg, and cloves. Set aside.
In a large bowl, combine pumpkin, sugar, maple syrup, egg, and olive oil. Add the flour mixture and stir. Cover the bowl and let the batter rest for 30 minutes.
While the batter rests, preheat the oven to 340°F (170°C). Grease and line an 8.5x4.5in (20x10cm) loaf pan with parchment paper.
Pour the batter into the prepared loaf pan and top with pepitas. Bake for 55-60 minutes, or until a skewer inserted in the middle comes out clean. Let the bread rest in the pan for 5-10 minutes before taking it out on a wire rack to cool completely.
Notes
If you're using a dark metal pan, bake the loaf at 320°F (160°C) for 45-50 minutes.