In a bowl, whisk together the flour, baking powder and salt. In another bowl, whisk together the egg yolks, milk, melted butter, sugar, vanilla extract and lemon zest. Whisk until all of the brown sugar breaks down and is no longer lumpy.
Beat the egg whites in the bowl of a standing mixer until stiff peaks form. Gently fold them into the wet mixture making sure to not over mix and deflate the egg whites.
Pour the wet mixture over the dry mixture and stir until just combined. Allow to sit for five minutes.
Meanwhile, heat your waffle iron. Ladle enough batter to cover three-quarters of the surface. Cook until your desired doneness and according to your waffle iron’s directions. Serve topped with real maple syrup or a dusting of confectioner’s sugar.