Preheat waffle iron according to manufacturer’s instructions.
Mix dry ingredients: In a large bowl, whisk together flour, sugar, baking powder, baking soda, and salt.
Prepare wet mixture: In another bowl, whisk together egg yolks, buttermilk, melted butter, and vanilla until smooth.
Combine: Pour wet mixture into dry ingredients. Stir until just combined (batter will be lumpy don’t overmix).
Whip egg whites: In a separate clean bowl, beat egg whites with an electric mixer until stiff peaks form.
Fold in egg whites: Gently fold whipped egg whites into batter until incorporated.
Cook waffles: Lightly grease the waffle iron with oil or cooking spray. Pour batter in (amount depends on your waffle iron size), close lid, and cook until golden brown and crisp, about 3–5 minutes per waffle.
Serve immediately with desired toppings.