Mix together the egg yolks, milk, oil, and vanilla.
In another bowl, beat the eggs whites until soft peaks form.
Combine the flour, baking powder, brown sugar and salt, then add to the milk mixture gradually. Gently fold in the egg whites.
Pour into a hot greased waffle iron. Before closing lid, generously sprinkle a cinnamon-sugar mixture over top of waffle batter, then close lid until cooked.
Notes
Note: To make buttermilk: in measuring cup add 1 Tbsp vinegar, add milk to 1 1/4 cup mark, let sit 5 minutes).