Combine the mashed banana, egg and protein powder in a bowl and whisk until smooth. The batter should be liquidy and not have banana chunks.
Spray the waffle iron and pour the batter into it. Cook according to your waffle iron's instructions.
Optional to serve with toppings.
Notes
Don't cook on the "crispy" or "dark" setting. This will make the protein waffles super dry. Choose the "light" or shorter cook time for the best protein waffles.