Break the noodles. Cook the noodles in boiling salted water for about 10 minutes, pour onto a sieve, rinse and drain well. In the meantime clean and wash the leek and cut the rings. Cook the leek in boiling salted water for about 2 minutes, pour on a sieve, quench and drain well.
Mix sour cream and eggs and season with salt, pepper and nutmeg. Mix the noodles and leek, place in a greased casserole dish and pour the egg milk over it. Sprinkle the casserole with cheese and bake in a preheated oven (electric: 200 °C/ gas: level 3) for approx. 40 minutes.
Meanwhile peel and finely dice the onions and garlic. Heat the oil in a pan, fry the onions and garlic, stir in the tomato paste and add the tomato pulp. Bring to the boil and season with ketchup, salt, pepper, paprika and sugar.
Let the sauce simmer at medium heat for about 4 minutes. Wash parsley, dab dry and chop finely. Serve the casserole sprinkled with parsley. Serve tomato sauce extra.