Whisk together the flour, sugar, baking powder, salt, cinnamon, milk, eggs, vanilla, and melted butter just until combined.
Core and finely dice the apples (you'll need 1 1/2 cups). Fold into batter. Heat a skillet over medium; spray with cooking spray. Pour batter on skillet. Cook until pancakes start to bubble, and then flip. Cook until golden brown.
Top with any remaining diced apples and maple syrup to serve.