Whisk together flour, sugar, baking powder, and salt in a large bowl until well combined.
In another bowl, mix milk, egg, melted butter, and vanilla extract until uniform.
Pour wet ingredients into dry ingredients and stir gently until just combined without overmixing.
Heat a non-stick skillet over medium heat and lightly grease it with butter or oil.
Ladle 1/4 cup batter onto the skillet for each pancake, spacing them evenly.
Cook until bubbles form on the surface, then flip and cook until golden brown on both sides.
Remove pancakes from skillet and immediately sprinkle cinnamon sugar on each while warm.
Repeat with remaining batter, greasing skillet as needed.
Arrange pancakes on a platter and serve warm.