Boil the potatoes (amount as required) in salted water.
Slit open sausages, take out the sausage and fry in hot oil in a pan. In the meantime, cut the leek into rings, add to the roast and simmer for 6 - 8 minutes. Then add the cream and crème fraîche, bring to the boil and season with salt and nutmeg. Pour the whole thing over the potatoes, done.