Preheat the waffle iron according to the manufacturer's instructions. In 1 medium bowl sift together flour, baking powder, and salt. Set aside. In a second bowl use the wooden spoon to beat together the egg yolks and sugar until sugar is completely dissolved and eggs have turned a pale yellow. Add the vanilla extract, melted butter, and milk to the eggs and whisk to combine. Combine the egg-milk mixture with the flour mixture and whisk just until blended. Do not over mix. In third bowl, beat the egg whites with an electric mixer until soft peaks form, about 1 minute. Using the rubber spatula, gently fold the egg whites into the waffle batter. Do not overmix! Coat the waffle iron with non-stick cooking spray and pour enough batter in iron to just cover waffle grid. Close and cook as per manufacturer's instructions until golden brown, about 2 to 3 minutes. Serve immediately.