Preheat your waffle iron. Whisk together flour, sugar, baking powder, and salt in a large bowl.

In a separate bowl, whisk egg yolks, milk, melted butter, and vanilla together.

Pour wet ingredients into dry ingredients and stir until just combined (a few lumps are fine).

Beat egg whites with a hand mixer until stiff peaks form. Gently fold into the batter — this is the secret to extra-fluffy waffles.

Cook in the waffle iron according to manufacturer's directions until golden and crisp.

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