Preheat waffle iron.
Combine all dry ingredients in a bowl and mix well (ground flax, cinnamon, oat flour, and baking powder).
Mix your almond milk (or whatever milk you are using) with apple cider vinegar. Then quickly add almond milk, egg, and coconut oil to the dry ingredients. Mix until just combined, then add in vanilla extract and maple syrup.
Spray your waffle iron with non-stick cooking spray. I used avocado oil. Pour the ENTIRE mixture onto the waffle iron. Use a spatula to spread out the batter evenly accross the entire waffle iron.
Cook for 8-10 minutes or until the waffle maker says, "ready." Keep in mind that these are denser than typical white flour waffles, so they will take longer too cook!
Store in the fridge up to one week, reheat in the toaster, it may take two rounds in the toaster to get crispy again.
Store in the freezer up to 3 months - can toast directly from frozen, it will take a few rounds though because they are thicker than typical waffles! A toaster oven would work too!