Peel onion and parsnips. Wash the parsnips, set aside 1 medium parsnip. Dice onion and parsnips. Heat butter. Sauté the onion cubes in it. Add the parsnips and fry briefly. Deglaze with stock and white wine, season with salt and pepper. Cover and cook for about 30 minutes.
Cut the rest of the parsnip into thin slices. Heat the oil in a small pot. Fry the parsnip slices for 5-6 minutes, turning occasionally, until crispy. Remove and season with salt. Wash parsley, shake dry. Pluck off the leaves and chop finely
Mix cream and starch. Finely puree the soup, pass it through a sieve into a pot, add the cream mixture, bring to the boil again, season with salt, pepper and a little sugar
Mix crème fraîche with milk. Arrange soup in soup bowls. Pour the crème fraîche onto the surface using a spoon handle or the tip of a knife. Sprinkle with parsley and parsnip chips