In a large mixing bowl, combine the dry ingredients: whole wheat flour, baking powder, salt, and cinnamon. Whisk them thoroughly until they're well combined, leaving no lumps.
In another bowl, take the egg whites and beat them with a hand mixer until fluffy and stiff peaks form. This might take a few minutes, but it’s crucial for fluffiness.
In a separate bowl, combine the mashed banana, milk, oil, and vanilla. Mix until smooth and well-integrated.
Gently fold the beaten egg whites into the banana mixture, being careful not to deflate them. You want to keep that airy texture.
Now, pour the wet mixture into the bowl of dry ingredients. Use a spoon to gently stir until just combined. Be cautious not to over-mix; a few lumps are perfectly fine.
Heat a non-stick skillet over medium heat. Once hot, spray lightly with olive oil or cooking spray.
Pour about 1/4 cup of the batter onto the skillet for each pancake. Cook until you see bubbles forming on the surface and the edges start to look set, about 2 to 3 minutes.
Carefully flip the pancakes once they have a golden-brown color and cook the other side for an additional 2 to 3 minutes until browned. They should be fluffy and cooked through.
Repeat the process with the remaining batter, adjusting the heat as necessary to ensure even cooking. Serve warm with your favorite toppings.