Melt the butter over low heat and let it cool.
Put milk and water in a pot and warm it until slightly lukewarm, completely dissolve the yeast in it.
Separate the eggs, beat the yolks lightly and add them to the milk-yeast mixture.
Put the flour in a large bowl, add part of the milk, whisk out all the lumps, add the rest of the milk and the cooled melted butter.
Whip the egg whites stiff with a pinch of salt, gently fold the foam into the batter.
Let it rest for an hour in a warm place covered with a towel.
Preheat the waffle iron well, lightly grease both sides with peanut oil.
Fill the mold well with the batter, close it, turn it over and bake them crispy.
Serve them with powdered sugar and whipped cream if you like.