Preheat the waffle iron according to the manufacturer's directions (or to 400°F if your waffle maker has a temperature gauge).
Place flour, baking powder, sugar, and salt in a large bowl. Whisk to combine.
In a small bowl, mix egg yolks, milk, butter, and vanilla extract. Set aside.
In a separate medium bowl, beat egg whites with a mixer on medium high speed until stiff peaks form. Beating the egg whites and folding them in makes the fluffiest waffles. This recipe can be made without beating the egg whites as well. If you do not beat the egg whites, reduce milk to 1 1/2 cups, and add whole eggs to the butter mixture.
Add the egg yolk mixture to the dry ingredients and stir to combine. Gently fold in the egg whites.
Drop by large spoonfuls onto greased waffle iron until most of the wells are covered. Close the lid and cook for about 3-5 minutes or until golden brown.