Peel and chop the kohlrabi generously, then put the butter in a saucepan and sauté the kohlrabi well. Peel and dice the rest of the vegetables and add to the saucepan; Fill with a cup of water and cook covered for about 15 minutes. Stir again and again.
Now add the broth and the cream, stir well and cook for half an hour. Season with pepper, nutmeg and parsley.
When everything is quite soft, puree roughly with a hand blender.