Feel free to sub in half whole wheat flour if you like.
2 large eggs, separated
4 tablespoons unsalted butter, melted
3/4 cup buttermilk, warmed
1 cup whole milk, warmed
1 teaspoon vanilla extract
2 cups all-purpose flour
1 tablespoon granulated sugar
1/2 tablespoon baking powder
1 teaspoon baking soda
1/4 teaspoon salt
Preheat the oven to 200°F.
In a small bowl, whisk together the egg yolks, melted butter, buttermilk, milk, and vanilla. In a medium bowl, whisk together the flour, sugar, baking powder, baking soda, and salt. In another medium bowl, whip the egg whites several minutes with an electric mixer until they hold soft peaks that droop slightly when the beaters are lifted.
Stir the milk mixture into the flour mixture until combined. Stir in a big spoonful of beaten egg whites until incorporated. Then, with a flexible spatula, gently fold in the remaining egg whites.
Grease the waffle iron either with cooking spray or brush with oil. Scoop 1/2 to 2/3 cup of batter into the hot iron. Cook according to the manufacturer's instructions or until golden and crispy on the outside. Keep warm in a single layer on a sheet pan in the oven until ready to serve. Top with butter and maple syrup, or whatever fresh fruit is in season. Jam is also acceptable. Whipped cream doesn't hurt, either.
Source: Adapted from The Homemade Pantry: 101 Foods You Can Stop Buying and Start Making by Alana Chernila