BUTTER: Pre-heat the oven to 200 degrees F and prepare a large baking sheet by setting a cooling rack on top of the tray. Place both in the oven. Start by melting the butter and then setting in the fridge or aside at room temperature to cool. It should be at room temperature before adding to the wet ingredients.
WET: Place the bananas in a small bowl and mash completely with a fork or beat with a hand mixer until smooth. Measure and confirm that you have exactly 1 level cup. Add back to the bowl. Stir in buttermilk, lightly beaten egg, white sugar, and vanilla extract. Once the butter is cooled to room temperature, drizzle into the other wet ingredients while stirring constantly.
DRY: In another medium-size bowl, add the flour, baking powder, salt, and cinnamon. Whisk until combined. Make a well in the dry ingredients. Pour the wet ingredients into the well. Mix ingredients until JUST barely combined and no flour streaks remain. Do not overmix! If you have the time, let the batter stand at room temperature for 5-10 minutes.
COOK: Heat a large skillet or griddle over medium-high heat (~300 degrees F). When hot, run the cold stick of remaining 3 tablespoons butter across the skillet/griddle (I like to hold butter with tongs to keep the heat away from my fingers). Lower the heat to medium-low and use a 1/4 cup measuring cup to scoop and drop pancake batter onto the skillet or griddle. Cook until the surface of pancakes are firm underneath with some bubbles on the surface, about 1 to 2 minutes. Gently flip with a spatula and cook until browned on the other side, about 1 to 2 minutes more. Continue making pancakes until the batter is gone. (If the pancake or butter is burning, lower the heat.) Wipe griddle or skillet in between batches of pancakes with a paper towel or napkin (you don't want burned butter pancakes).
COOK CONT.: As soon as you take a pancake off the skillet/griddle, place it on the prepared pan with the cooling rack (the cooling rack keeps pancakes from getting soggy underneath). Place the pan in the oven as you continue to cook more pancakes.
SERVE: Serve pancakes as soon as possible, topped with an extra pat of butter (optional) and your favorite syrup -- maple syrup is our favorite. Add a few extra slices of bananas, whipped cream, crushed almonds or walnuts, or whatever you'd like on your Banana Pancakes!