Preheat your oven to 350°F (175°C) and grease a 9x5 inch loaf pan.
In a large bowl, combine the grated zucchini, almond flour, protein powder, Greek yogurt, honey, eggs, and vanilla extract. Mix well until all ingredients are fully incorporated.
In a separate bowl, whisk together the baking soda, baking powder, salt, and cinnamon. Gradually add the dry ingredients to the wet mixture, stirring until just combined. If using, fold in the chopped nuts.
Pour the batter into the prepared loaf pan and smooth the top. Bake for 50-60 minutes, or until a toothpick inserted in the center comes out clean.
Allow the bread to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.