Add all the dry ingredients to a large bowl, except the chia seeds or nuts (if using). That will be added in the end.
In a second bowl add in the bananas and mash it using a fork, until creamy and very little chunks left (though some banana chunks will give the muffin a good texture).
Whisk in the milk, honey or maple syrup and vanilla extract.
Pour liquid ingredients into dry bowl and fold, using a spatula until well combined. DO NOT over work the dough. If using chia seeds or nuts, add that in as you start to fold the liquid and dry ingredients.
Use an ice cream scooper to easily pour batter into individual muffin cups that are lined with paper muffin liners or silicone molds. Fill more than 3/4 full (almost all the way to the top).
Bake at 375F degrees for 23-25 minutes. Insert toothpick to see if the muffins are cooked internally (see notes)**