In a large mixing bowl, add the flour, sugar, cinnamon, salt, baking powder, and baking soda and whisk to combine. In a separate medium bowl, add the buttermilk, vanilla, melted butter, and egg yolks and whisk to combine.
Add the buttermilk mixture to the dry ingredients and gently fold with a rubber spatula until just combined. Add the egg whites and fold until just combined. Be sure not to over mix. Some lumps are okay.
Let the batter rest for 15-30 minutes at room temperature.
Add a tablespoon of butter (more if desired) to a cast iron skillet and heat over medium low heat. Once the butter has melted and is bubbling, reduce the heat to medium-low and add ⅓ cup of the pancake batter to the pan. Cook for about 2-3 minutes, or until bubbles start to appear on the surface, or the exterior of the pancakes. Using a spatula, flip the pancake over and cook for another 2 to 3 minutes, or until golden brown. Repeat with the remaining pancake batter until finished. Serve the pancakes with butter and some maple syrup. Enjoy!