Preheat the waffle iron fully
Separate the eggs
Whisk the dry ingredients together: flour, sugar, baking powder, salt
Whisk the wet ingredients together: egg yolks, milk, melted butter, vanilla
Combine the wet and dry ingredients until just mixed
Beat the egg whites until stiff peaks form
Fold the egg whites gently into the batter
Let the batter rest for 5 to 10 minutes
Lightly grease the waffle iron
Pour in the batter without overfilling
Cook until the waffles are deep golden brown and crisp
Remove the waffles and place them on a wire rack
Keep finished waffles in a warm oven on a rack to stay crunchy
Serve immediately