Sift together the flour, baking powder and salt into a mixing bowl.
Beat the egg yolks until pale yellow, then add to the milk and beat well.
Pour the egg yolk and milk mixture onto the flour and blend thoroughly.
Stir in the melted butter or vegetable.
Set aside for about an hour.
Beat the egg whites until stiff and fold into the batter with the bacon pieces.
Fill a hot, oiled waffle iron two-thirds full and cook until the steam stops escaping from the sides.