Some say it doesn't matter whether you separate the egg and whip the white before folding it into the waffle batter. I find, however, that waffles made with a whipped egg white are not only lighter and more airy, they're also taller and more tender. Plus, they brown better. Many waffle recipes contain sugar, but most include it with the dry ingredients. I find that beating it with the egg white accomplishes two things. First, it stabilizes the white, improving the batter's longevity. Second, the sugar softens the egg white, making it much easier to fold into the batter.
A thinner batter generally results in a crisper waffle. For this reason, I find that liquid fat (e.g., vegetable oil) rather than solid fat (shortening or butter) delivers the crispest waffle. And up to a point, the more fat, the better. For a five-waffle recipe, six tablespoons of vegetable oil is ideal.
Unlike most waffle recipes that call for either milk or buttermilk, this recipe calls for both. Buttermilk waffles are more flavorful, but the batter is thick and the waffles less crisp. Waffles made with milk, on the other hand, are more crisp but less flavorful than buttermilk waffles. A combination of the two milks offers the best of both—milk for crisp texture, buttermilk for full flavor.