Mix dry ingredients (flour, sugar, baking powder, baking soda, salt, and cinnamon) together in a large bowl.

In a separate bowl, use two forks to mash the banana. Add the remaining wet ingredients (egg, buttermilk, vanilla, and melted butter) to the banana and stir well to combine. Some small lumps of bananas may remain.

Pour the wet ingredients into the dry ingredients. Mix the pancake batter until smooth.

Heat a large skillet over medium heat. Lightly oil the skillet with butter or olive oil. Use a large cookie scoop or a ¼-cup measuring cup to pour the batter onto the hot pan.

Cook the pancake until bubbles begin to form and the edges of the pancake begin to set. Flip the pancake and continue to cook on the second side until golden brown. Repeat until all the pancakes are cooked.