Clean, peel, wash and cut the kohlrabi into strips. Clean, wash and cut the spring onions into rings. Heat the butter in a saucepan and sauté the kohlrabi strips with the spring onions in them. Season with salt, pepper and nutmeg. Pour the beef stock over everything and let it steep for about 10 minutes over a mild heat. Wash, dry and finely chop the thyme. Stir the cream into the soup and puree everything with the cutting stick. Serve garnished with thyme.