In a medium bowl, mix together the flour, baking powder, sugar and salt. In a separate bowl, beat the egg whites until stiff peaks form. In another bowl, whisk together the egg yokes and milk. Gradually add the dry ingredients to the egg yoke mixture and stir until combined. Gently fold in the beaten egg whites.
Heat a lightly oiled waffle iron. Pour 1/4 cup of batter onto the hot waffle iron. Cook until golden brown. Repeat with remaining batter.
To assemble sandwiches: Place one waffle on a plate and top with two scoops of ice cream. Top with another waffle and press down gently.