Mix flour, milk (or white wine, beer or soda water), oil, egg yolks and salt briefly until a smooth dough. (Often the dough is flavored the same way with a cl of rum.) Do not stir the dough longer than is absolutely necessary or it will become tough when baked. Next, rest a tiny bit.
Before using, gently and briefly fold the beaten egg whites, beaten hard with sugar for desserts, into the dough to prevent it from becoming tough and cracked.