Preheat oven to 350 degrees F. Line a muffin pan with paper liners or spray with cooking spray. Set aside.
Make flax egg by combining ground flaxseed and water in a small bowl. Mix and set aside for 5 minutes to thicken.
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon. Set aside.
In a large bowl, combine mashed bananas, coconut sugar, flax egg, coconut oil, almond milk, and vanilla. Stir until well combined. Add the flour mixture and stir with a spatula until flour is just combined. Do NOT overmix! Squeeze the zucchini in a paper towel to remove excess liquid. Fold the zucchini into batter. Gently fold in the blueberries. (If using frozen blueberries, toss them in a little bit of flour before adding it to the batter.)
Pour the batter into prepared muffin tin, about 3/4 full. You can sprinkle the tops with extra coconut sugar or blueberries if you want. Bake for 20-25 minutes or until a toothpick inserted into the center comes out clean. Let muffins cool in the pan for 10 minutes, then remove muffins and place on a wire rack to cool completely. Enjoy! Store in an airtight container on the counter for up to 3 days.