In the bowl of a stand mixer (or handheld mixer) fitted with the whisk attachment, whip egg whites on high to stiff peaks. Transfer the egg whites into another bowl and set aside.
In the same bowl used for the egg whites, add the egg yolks and sugar and, using the paddle attachment, beat until smooth and lighter in color. Add the buttermilk, vanilla extract, and melted butter and mix to combine.
Dump the flour in all at once, followed by the baking powder and salt. Mix by pulsing on and off just until combined. Don't overmix.
Fold egg whites into the egg yolk and flour mixture gently to avoid deflating egg whites.
Heat waffle iron. When ready, dollop large spoonfuls into waffle impressions and close the lid. Bake for recommended time per waffle iron instructions.
Remove waffles carefully from iron and finish baking the rest of the waffles. To keep waffles warm and crisp, place on a wire rack over a baking sheet and into a 200° F oven in one single layer. Serve with butter and real maple syrup.
To freeze, lay in a single layer on a parchment-lined baking sheet and freeze until solid. Place frozen waffles in a galllon ziptop bag and remove as much air as possible. To reheat, place in a toaster or toaster oven and heat until warmed through and crisp.