Clean and wash the leek and cut into fine rings. Peel and finely chop the onion. Heat half of the fat. Steam the leek for about 2 minutes. Take out. Steam onion in the remaining fat until transparent.
Add the caraway seeds. Dust with flour. Add stock and cream and bring to the boil while stirring. Grate cheese and add. Let it swell for about 10 minutes at low heat. Stir several times in between.
Season soup with salt and pepper. Finally add leek again. Wash parsley, dab dry and chop. Add to the soup just before serving.