For the waffles, like grandma did, separate the eggs into whites and yolks. Beat the egg whites until stiff and set aside.
Beat the butter with the granulated sugar, vanilla sugar and a pinch of salt for a few minutes with a hand mixer until creamy. Gently fold in the three egg yolks and continue mixing until the granules of granulated sugar are no longer visible.
Add a pinch of baking powder to the flour and gradually mix it into the egg-sugar mixture, alternating with the milk. To make the dough even fluffier, add the mineral water and mix with the dough.
Finally, add the beaten egg whites to the mixture and gently stir in.
Butter the waffle iron well and bake one waffle after the other until the batter is used up.