Clean, wash, peel and chop the carrots and celery. Bring the stock to the boil, add the vegetables and simmer covered for about 25 minutes. In the meantime, whip the cream semi-solid, except for 2 tablespoons.
Puree the vegetables in the stock with the cutting stick of the hand mixer. Refine with remaining cream. Bring to the boil once and season with salt and pepper. Pour soup into plates. Place one tablespoon of cream in the middle of each plate and serve sprinkled with cress.