Preheat oven to 350 degrees. Line an 8 x 4-inch loaf pan with parchment paper and allow the paper to hang over the sides for easy removal. In a small bowl use a fork, stir together 26 grams (1/4 cup) of the flaxseed meal and the water until fully combined. Let sit for 10 minutes or until gummy in texture.
In a large bowl sift together the remaining dry ingredients until there are no lumps. Stir in the butter, yogurt and vanilla (if using) until all the dry ingredients are moist.
Check on the flaxseed and water mixture. Make sure it has set for at least 10 minutes and is gummy in texture. Pour the flax seed and water mixture into the dough then sprinkle in the xanthan gum. Stir until fully combined then continue to stir another 30 seconds until a smooth moist dough forms.
Gradually fold in the zucchini until fully combined and evenly distributed throughout the dough. Scrape down the sides of the bowl and push the dough to the center of the bowl. Let sit 5 to 10 minute to absorb any extra moisture.
Test the texture of the dough by rolling a portion of the dough in hands until a smooth ball forms. Form the dough into an oval texture and place into prepared loaf pan. Pres evenly and smoothly throughout the loaf pan. Place in preheated oven and bake at 350 degrees for 50 to 55 minutes until a tester comes out clean.
Remove from the oven. Allow to cool in the pan at least 1 hour to firm up. Grasp over hanging parchment paper and transfer to a wire rack. Allow to cool completely before slicing. Once cooled slice into desired size slices. Store leftovers in an airtight container at room temperature up to 3 days or in the refrigerator up to 1 week
This bread has a very moist center. If it is too moist for you once the bread is cooled and sliced place the slices on a lined baking sheet and bake at 350 for another 5 to 10 minutes or until desired texture.