Peel the onion, finely chop. Heat the butter in a frying pan; fry the onion, 2 min. Squeeze the cabbage and add to the onion. Cook for 2 more minutes. If the cabbage is chopped into very long strips, it must be cut into smaller pieces before frying.
Peel potatoes, grate on a coarse grater. Transfer the cabbage with onions and potatoes to a large bowl, beat in the eggs and mix thoroughly.
Preheat the oven to 180 C. Put the resulting mass into a baking dish, level the surface and sprinkle with ground paprika. Bake 15 min.