Mash the bananas: In a large bowl, mash the bananas with a fork until mostly smooth. A few small lumps are fine.
Whisk in wet ingredients: Add the egg, milk, and vanilla. Whisk until combined and creamy.
Mix dry ingredients separately: In another bowl, whisk flour, sugar, baking powder, baking soda, cinnamon, and salt.
Combine gently: Add dry ingredients to the banana mixture. Stir with a spatula until just combined. Do not overmix; a few streaks of flour are okay.
Rest the batter: Let the batter sit for 5 minutes. This helps it thicken and gives fluffier pancakes.
Preheat the pan: Heat a nonstick skillet or griddle over medium heat. Lightly grease with butter or oil.
Cook the pancakes: Pour about 1/4 cup batter per pancake. If using add-ins like chocolate chips or nuts, sprinkle them on now. Cook until bubbles form on the surface and edges look set, 2–3 minutes.
Flip and finish: Flip and cook 1–2 minutes more, until golden and cooked through. Adjust heat as needed to prevent burning.
Serve warm: Stack them up and add your favorite toppings. Maple syrup and extra banana slices are a classic.