Get Ready: Preheat your oven to 350°F (175°C). Prepare an 8x4-inch loaf pan by greasing it lightly or lining it with parchment paper for easy removal.
Prep Zucchini: Grate your zucchini using the largest holes on a box grater. Gently squeeze out any excess moisture with a clean kitchen towel or cheesecloth to keep your bread from getting soggy.
Mix Dry Ingredients: In a large bowl, whisk together the almond flour, sugar-free sweetener, baking powder, cinnamon, and salt.
Combine Wet Ingredients: In a separate medium bowl, beat the eggs. Then, stir in the prepared zucchini, melted butter, and vanilla extract until well combined.
Bring it Together: Pour the wet ingredients into the dry ingredients. Stir gently until everything is just combined – be careful not to overmix! If you're using walnuts, fold them in now.
Bake & Cool: Transfer the batter evenly into your prepared loaf pan. Bake for 45 to 55 minutes, or until a toothpick inserted into the center comes out clean. Let the bread cool in the pan for 5 minutes before carefully removing it to a wire rack to cool completely.