Grease a standard loaf pan and line it with a parchment paper sling.
In a large bowl, whisk the ½ cup olive oil with 1 cup brown sugar. Add the 3 large eggs one at a time and whisk well to combine. Whisk in the 1 cup pure pumpkin puree. Now add the 2 ¼ cups oat flour, 2 teaspoons baking powder, ½ teaspoon fine sea salt, ¾ teaspoon ground cinnamon, ½ teaspoon ground ginger, and ¼ teaspoon ground nutmeg and stir to combine.
Pour the batter into the prepared pan. Smooth the top. Preheat the oven to 350℉, letting the batter rest in the pan while the oven preheats.
When the oven is ready, place the pan in the oven and cook for 50-60 minutes, checking at 50 minutes, until a tester inserted in the center comes out clean and the top is firm.
Remove the loaf from the oven and place on a wire rack to cool. Cool for about 15-20 minutes in the pan, then turn out on the rack to cool completely before cutting.
Bread will keep, well wrapped in the fridge, for up to 5 days.
Notes
Don't overbake. Oat flour can get a bit dry if you bake it for too long. I advise checking with a tester around 50 minutes and checking thereafter every 5 minutes until it's done.
Cool completely. Though tempting to slice right into that warm, fragrant loaf, resist the impulse! The crumb will set as it cools, ensuring there's no gumminess.
Make it refined sugar-free. It's so easy to make this loaf with coconut sugar or maple syrup. Simply swap 1 cup of coconut sugar or ¾ cup of maple syrup for the brown sugar.
Use gluten free flour. If needed, substitute the combination of oat and almond flour for 1 ¾ cups of gluten free all-purpose flour (my homemade gluten free flour blend is a nice choice).
Use pumpkin pie spice. Use pumpkin pie spice in place of the combination of spices in the batter if you prefer.