Peel the onion and cut it finely, then wash the leek and mince it. Peel also the potatoes, reduce them in pieces and wash them under a jet of cold water so they don't become darker.
In a pan with butter brown the onion and leek, add the potatoes and afterwards pour the white wine and chicken broth; cook until the potatoes soften. At this point blend and sift the soup. Add to it the milk, cream and a pinch of salt and pepper.
Put the soup back on the stove in order to heat it and if you like, pour a little wine so to give it more taste. Whip the remaining cream and serve. Finally garnish with some aromatic leaves and sprouts.