Preheat oven to 350 F. In a small bowl combine 1 tbsp of ground flax with 2 1/2 tbsp of water. Whisk with a fork, and set aside allowing to sit for 5 minutes.
While flax egg sits make your vegan buttermilk. In a small mixing bowl combine 1 tbsp of apple cider vinegar with 1/3 cup of almond milk. Whisk with a fork and set aside for 5 minutes. Milk will curdle and turn into buttermilk.
While flax egg and vegan buttermilk are sitting, shred your zucchini. Using a cheese grater of the grating attachment on your food processor grate 1 medium zucchini. Measure out 1 cup of grated zucchini packed.
In a large bowl, sift the flour, baking powder, baking soda, cinnamon, nutmeg, and salt. Set aside.
In a medium mixing bowl mash banana until it is completely mashed without any lumps. Or use a food processor to liquify the banana and then transfer to medium mixing bowl. After flax egg, and buttermilk have had time to sit, add them to the bowl with the banana, and add the maple syrup. Whisk to combine.
In the large bowl with the sifted flour create a well by pushing the flour to the sides. Add the wet ingredients to the center of the well. Slowly fold the wet and dry ingredients together until combined. Do not over mix. When wet and dry ingredients are combined fold in shredded zucchini.
In the large bowl with the sifted flour create a well by pushing the flour to the sides. Add the wet ingredients to the center of the well. Slowly fold the wet and dry ingredients together until combined. Do not over mix. When wet and dry ingredients are combined fold in shredded zucchini. Add 1/4 cup of chocolate chips of chopped nuts if you choose.
Line your muffin tins with muffin cups. I like to use parchment paper muffin cups. Fill muffin cups 3/4 of the way full. You should have enough batter for 12 muffins.
Bake for 30-35 minutes on the center rack of your oven, or until tops are golden brown. Remove from oven, transfer to a cooling rack, and allow to cool completely before serving.