Preheat waffle iron

In a large bowl, whisk together the flour, sugar, baking powder, salt, and baking soda until well combined

In a medium, whisk the egg yolk,until combined, and then whisk in buttermilk. Gradually add in the butter.

Pour the liquid ingredients into the dry ingredients and whisk gently just until the batter is evenly moistened. I's okay if there's lumps. The batter will be quite thick.

In a clean medium bowl, with a clean whisk, rotary beater, or hand held mixer, beat the egg whites until they hold soft peaks. Using a rubber spatula, slide the beaten egg whites into the batter and gently fold them in.

Pour a generous .5 cup of the batter into the waffle iron. Using a rubber spatula to even it out and cook to desired doneness (they usually take an extra 15-20 seconds after the indicator dings)

Remove and Serve