In the mixer beat egg yolks, milk, vanilla, butter and sugar until combined. In a large bowl mix flour, baking powder and salt. Whisk egg yolk mixture into dry ingredients until no lumps remain. Beat egg whites until they are medium stiff. Add to batter in 3rds folding gently. Heat both sides of the egg waffle pan on the stove over medium heat. Baste pan with butter. Pour 3/4 cup of batter into a pan, place the other side over the top and gently squeeze. Cook for 1-2 minutes on either side or until golden brown. Remove to a plate and top with whatever you wish.