Cut onions into slices. Heat butter, sauté onions until translucent. Add clear soup and wine, fold in crème fraîche and continue cooking for 20 minutes. Grate potatoes, add to soup and continue cooking for about 20 minutes.
Cut cabanossi into slices, add and heat. Season soup with salt, pepper and chopped marjoram.
Garnish: Baguette with garlic butter.