Remove dark green leaves from leeks and the end of the white part. Then halve the rest lengthwise. Now cut leeks into fine slices. Heat oil in a pot, sautée leeks from all sides and add vegetable soup. Simmer for 20 minutes and add green peas for the last 5 minutes. Meanwhile cream butter and egg. Add semolina and cheese bit by bit, season to taste with salt and pepper. Allow to rest 20 minutes. Bring salted water to the boil, form walnut sized balls. Poach these dumplings in salted water for 15 minutes. Refine the taste of soup with salt, pepper and nutmeg. Serve with chopped chives.