Use whisk attachment with your stand mixer (or use hand mixer) to beat egg whites until stiff peaks form. Set aside.
Place the butter and brown sugar in a large bowl (this will be your final bowl) in the stand mixer. Mix on high with whisk attachment until light and fluffy. If you don't have a stand mixer use a hand mixer.
This is a good time to preheat and grease your waffle iron.
While your mixer is creaming the butter and brown sugar use a separate bowl to mix the flour, baking soda, baking powder and salt. No need to sift, just mix it well.
Once your butter and brown sugar is creamed, beat in the egg yolks.
Set the speed on your stand mixer to low-medium. Alternately blend in the dry ingredient mixture and buttermilk.
Once the rest of the ingredients are mixed, set your mixer to low and fold your egg whites in.
Cook until golden and enjoy. If you're planning on freezing some, undercook those slightly so when you toast them they're not overdone. Let them cool before freezing.