Whisk together the flour, baking powder, and salt in a large bowl.
In a separate bowl, whisk together the buttermilk, eggs, and maple syrup, and then pour into the bowl of dry ingredients.
Carefully fold the wet and dry ingredients together while drizzling in the melted butter, just until blended (do not overmix). We drizzle the butter so it won't turn solid again when contacting the cold ingredients. If this happens it will not mix as well, but don't worry, the recipe won't be ruined.
Heat a cast-iron skillet over medium-low heat and add a few teaspoons of butter to the pan. Add pancake batter using a soup ladle.
When the bottoms have started to brown, flip over and repeat. Cook in batches until the batter is gone, adding extra butter each time to keep the pan from getting dry.
For the Cinnamon Apples
In a large skillet, melt the butter over medium heat. Add in the apples and cook while stirring occasionally until they begin to soften, 4 or 5 minutes.
Add in the syrup and cinnamon, and stir to coat. Continue cooking until the apples can easily be pierced with a fork, another minute or so.
Serve warm over top of the pancakes with additional maple syrup, if desired.