In a large bowl, whisk together the flour, sugar, baking powder, and salt.
Separate eggs and add whites to a medium sized bowl, preferably stainless steel. Whip egg whites with an electric mixer until light and frothy, but not forming stiff peaks.
Add milk, melted butter, vanilla, and egg yolks to the dry ingredients. Mix using electric mixer on low speed until fully incorporated. (No need to clean mixer after whipping egg whites)
Gently fold in whipped egg whites into the batter using a spatula.
Preheat the waffle iron to a medium setting or according to manufacture's instructions. Lightly spray with cooking spray.
Pour about a ¼ cup into the center of the waffle iron and close. Cook for about 2 minutes or until golden brown.
Remove from waffle iron and serve with desired toppings.