Preheat the oven to 325F. Place muffin liners in your muffin tin. Or you can spray the tin.
Start with the flax “eggs”. Place the 5 tbsp water and 2 tbsp flaxmeal into a large bowl and mix together. Let sit for about 5 minutes.
Mash the bananas in a separate bowl (or mash them directly in the large bowl after the flax eggs have rested for 5 minutes). If mashed in a separate bowl, add them to the large bowl.
Now mix in the maple syrup, oil, and milk.
Mix in the baking soda, vanilla extract, cinnamon, oats, and whole wheat flour. Stir it well until combined. Then add the flaxmeal until mixed well together.
Add the mix-ins: walnuts, chocolate chips, etc.
Divide the batter evenly into the muffin liners. Recipe makes 12 large muffins or about 15 smaller muffins. If you want you can sprinkle some extra oats and/or chocolate chips on top.
Bake in oven for roughly 22-25 minutes depending on how hot your oven is. Insert a toothpick at the end to check that they are properly baked (toothpick should come out clean).
Let muffins cool and enjoy.
You can store them at room temperature for about 2 days, in the fridge for up to 4 days, and in the freezer for a month.