Beat egg whites until stiff. Put yogurt, egg yolks, flour, salt and baking powder in blender and mix unti lsmooth. Pour blended mixture into a bowl and gently fold in the beaten egg whites. Cook in a preheated Teflon waffle iron, or lightly oil reg. Waffle iron. Try spreading each waffle with 2 T. non-fat sour cream and artificially sweetened maple syrup.