Prepare the dough. Grate the apple on a fine grater. In a separate bowl, mix the eggs and sugar, beat them thoroughly. Pour in the milk and melted butter, mix again, then add the sifted flour, vanilla and baking powder. Add salt and mix until smooth. Add the grated apple and mix again.
Bake the waffles. Heat the waffle iron, remembering to grease the panels with vegetable oil. Spoon the dough. You will need 1-2 tablespoons per waffle. It takes an average of 3 minutes per batch to cook the waffles. But be careful that they do not burn.