Mix buttermilk and oats in a medium bowl; let stand for 15 minutes.Advertisement
Preheat waffle iron. Preheat oven to 200 degrees F.
Whisk all-purpose and whole-wheat flours, baking powder, baking soda, salt and cinnamon in a mixing bowl. Stir in nuts, if using.
Whisk egg, egg white, brown sugar, oil and vanilla into oats. Whisk into dry ingredients until just moistened.
Lightly coat waffle iron with nonstick spray. Spoon in batter and cook until the waffle is crisp and golden. Transfer to oven to keep warm. Repeat with remaining batter, lightly coating iron with nonstick spray each time, if necessary.
2 other carbohydrate, 1 fat