Preheat waffle iron.
In a medium bowl, sift together flour, baking soda, baking powder and salt; set aside.
In a large bowl, cream butter and brown sugar until light and fluffy.
Beat in egg yolks.
Blend in flour mixture alternately with buttermilk and vanilla.
In a large glass or metal mixing bowl, beat egg whites until stiff peaks form.
Fold ⅓ of the whites into the batter, then quickly fold in remaining whites until no streaks remain.
Spray waffle iron with non-stick cooking spray, or lightly brush with oil.
Ladle the batter onto preheated waffle iron.
Cook the waffles until golden and crisp.
Serve immediately.
