Put the cottage cheese in a bowl and mash it with a masher (such as for potatoes). Add egg yolks (set whites aside), salt, sugar, vanilla sugar, flour and milk. Mix everything thoroughly with a whisk. At the end, add drained raisins if using.
Beat the whites separately into a stiff meringue. Add it to the cottage cheese mixture and mix gently with a spoon.
Heat a skillet with butter. When the butter starts to sizzle, clarify it (remove the foam). Spread the butter across the entire surface of the skillet, pour in the omelet mass, level the surface.
Fry on moderate heat for approximately 4 minutes or until the omelet is nicely browned on the bottom. Then flip it to the other side using a wide spatula - the omelet may break because in the next step we break it into smaller pieces anyway. Turn the pieces of omelet and brown from other sides, altogether for approximately another 4 minutes.
Transfer to a plate, sprinkle with powdered sugar, serve with jam and fruit.
