Place the warm milk in a small bowl and sprinkle 1 teaspoon of the granulated sugar and the yeast over the top; set aside for a few minutes so the yeast can activate.
In a bowl, using an electric mixer or whisk, beat the egg whites until stiff peaks form; set aside.
In a separate bowl, whisk together the milk-and-yeast mixture, the egg yolks, vanilla, butter and remaining sugar. Add the flour and salt and stir until the batter is mostly smooth (a few lumps won't hurt).
Gently fold in the egg whites, cover the bowl with plastic wrap and allow it to rest for about an hour or so in a warm spot, or refrigerate overnight.
When ready to make the waffles, preheat your waffle iron according to the manufacturer's instructions. Brush the plates of the waffle iron with a little butter or spray them with some cooking spray. Ladle in some of the batter (check the instructions of your waffle iron to know exactly how much batter to add) and cook golden brown. Repeat with the remaining batter. Serve the waffles with your choice of fresh fruit, confectioners' sugar or warm maple syrup!
These waffles taste great with Laura's Sausage-and-Apple Hash.