Prep Pan & Dry Mixture: Preheat your oven to 325°F (163°C). Lightly grease and line a 9x5-inch loaf pan with parchment paper, leaving an overhang for easy removal. In a medium bowl, whisk together the gluten-free flour, baking powder, baking soda, salt, cinnamon, and nutmeg.
Grate the Zucchini: Coarsely grate the fresh zucchini using the large holes of a box grater. Do not squeeze, blot, or strain out the moisture—you need all 180 grams of that natural hydration.
Mix Wet Ingredients & Zucchini: In a large bowl, vigorously whisk the 3 eggs, dark brown sugar, granulated cane sugar, olive oil, vanilla extract, and lemon juice until the mixture is completely smooth and emulsified. Whisk in the unsqueezed zucchini until evenly distributed.
Combine Wet & Dry: Add the dry ingredients to the wet mixture. Use a rubber spatula to gently fold everything together until a smooth, fairly runny batter forms with no flour pockets remaining.
Pour & Rest: Pour the batter into your prepared loaf pan and smooth the top. Let the batter rest undisturbed at room temperature for 20 minutes to allow the gluten-free flours to fully hydrate.
Bake: Bake uncovered at 325°F (163°C) for 50 to 60 minutes (my oven takes 55 minutes). Insert an instant-read thermometer into the exact center of the loaf—it should read between 200–205°F (93–96°C) to ensure the interior starches are fully set.
Cool: Rest the bread in the pan for 10 minutes, then transfer it to a wire rack. Cool completely at room temperature for at least 3 hours before slicing or wrapping to allow the crumb structure to lock in.