In a large bowl, combine the flour, sugar, baking powder, and salt.

In a separate bowl, whisk together the milk, beaten egg, melted butter, and vanilla extract.

Pour the wet ingredients into the dry ingredients.

Stir gently until just combined; avoid over-mixing.

Let the batter rest for 5-10 minutes.

Preheat the waffle iron according to the manufacturer's instructions.

Grease the waffle iron with melted butter or cooking spray.

Ladle the batter onto the hot waffle iron (approximately 1/2 cup per waffle, adjust per your iron).

Cook until the waffles are golden brown and crisp, following the waffle iron's instructions.

Repeat with remaining batter.

Serve immediately with warm maple syrup and a pat of butter, if desired.