Blend oats into a fine flour and transfer to a bowl.Mash bananas and whisk with eggs, milk, vanilla, and sweetener if using.Combine wet and dry ingredients, then let batter rest for five minutes.Heat a lightly greased skillet over medium-low heat.Pour batter into pancakes and cook until bubbles form.Flip and cook until golden and cooked through.Serve warm with your favorite toppings.