Preheat your oven to 350°F and grease 3 mini loaf pans with cooking spray or a thin coat of coconut oil.
In a large mixing bowl, whisk together the gluten-free flour, almond flour, baking soda, baking powder, cinnamon, nutmeg, and salt until evenly combined.
Add the brown sugar, white sugar, eggs, melted coconut oil, almond milk, lemon juice, and vanilla extract to the bowl.
Using a hand mixer on low speed, mix until just combined. Fold in the grated zucchini and mix for about 30 seconds on low. Stir in walnuts or chocolate chips by hand.
Divide the batter evenly among the prepared mini loaf pans. Bake for 25–30 minutes, until the centers are set and a toothpick inserted in the middle comes out clean.
Let the loaves cool in the pans for 10 minutes, then turn out onto a wire rack to cool completely.