Preheat the oven to 160 degrees Celsius and grease and line a regular loaf tin with baking paper.
Combine the gluten free flour, almond meal, chia seeds, baking powder and sea salt in a large mixing bowl.
In a separate bowl, whisk the eggs and add in the grated zucchini and apple cider vinegar.
Add the wet ingredients to the dry ingredients and stir till well combined. The mixture will form a thick, slightly wet dough.
Scrape the batter into the prepared loaf pan and flatten. Sprinkle with sesame or sunflower seeds if using.
Bake for one hour, until golden on top and baked through. The loaf should hold its shape when you press down on the top gently.
After removing it from the oven, allow to cool in the pan for 5 minutes before transferring to a wire rack to cool.