In another bowl mix together the butter milk, egg yolk butter and vanilla.
Using an electric mixer, whisk the egg white until soft peaks form (about 3-5 minutes).
Add the dry ingredients to the buttermilk mixture and whisk just until incorporated. You do not want it smooth.
Gently fold in the egg white
Let the batter sit for 5 minutes.
Spray your hot iron with non-stick spray.
Ladle in about 1/3 of a cup (or however much your waffle iron directions call for) and cook for 3-5 minutes or until done. Again, follow your machine’s directions.