In a blender (I use this one), add the first four ingredients: milk, butter, vinegar, and oats. Blend for a couple of minutes until all ingredients are combined and batter swirls making a vortex.
Allow the batter to sit with the lid on the blender overnight on the counter.
In the morning turn on your waffle iron and allow it to heat up. Add to the batter (still in the blender): eggs, vanilla, baking powder, baking soda, salt, banana, and honey. Blend until the all ingredients are combined (a minute or two).
Coat your waffle iron with butter. Pour batter into waffle iron. We use about 1/4 cup of batter per waffle. Cook waffles about 4-5 minutes until light brown.
Top with butter, pure maple syrup (where to buy) or raw honey. We also add chopped nuts, ground flax seed, and fresh fruit.