Sift together the flour, cornstarch, powder, soda, salt and sugar in a large bowl. In a medium bowl, combine the eggs, buttermilk, vanilla and melted butter, whisking as you add the butter.

Pour the wet ingredients into the dry and whisk just until the batter comes together. Do not over mix.

Heat a waffle iron to medium/medium high and coat with non-stick spray. Add 1 cup of batter to iron and smooth before closing. Cook until steaming stops. Remove and keep cooked waffles in preheated 200 degree oven on a rack while making the rest.