In a large bowl, whisk together the flour, sugar, baking powder, baking soda, salt, and cinnamon (if using) until well combined.
In a separate bowl, mash the ripe bananas with a fork until smooth. Add the milk, egg, melted butter, and vanilla extract, and whisk until fully combined.
Pour the wet ingredients into the dry ingredients and stir gently with a spatula or whisk until just combined. The batter should be slightly lumpy—do not overmix.
Heat a large non-stick skillet or griddle over medium heat and lightly grease with butter or oil. Scoop about 1/4 cup of batter per pancake onto the skillet, spreading it slightly into a round shape.
Cook for 2-3 minutes, until bubbles form on the surface and the edges look set. Flip the pancakes and cook for another 1-2 minutes, until golden brown and cooked through. Repeat with the remaining batter, greasing the skillet as needed.
Serve warm, stacked on plates, and top with maple syrup, sliced bananas, or chopped nuts if desired. Enjoy your fluffy banana pancakes!