Wash leeks, remove the dark green and cut into short pieces. Bring beef stock to the boil, add leeks and simmer for about 10 minutes. Peel potatoes and cut them into small cubes. Add to leeks and simmer for 10 minutes longer. Add bay leaf, salt, pepper and spice with nutmeg.
Chop onion finely and braise lightly. Add and fry minced meat. Spice with salt and pepper.
Preheat oven to 180°C. Decant vegetable, pour the soup over meat and let all simmer some minutes. Put vegetable cubes in a casserole dish, add minced meat with sauce.
Cook casserole in oven for about 30 minutes.