Heat 1/2 of the clarified butter, fry the sausages slowly for 2-3 minutes. Add the leek and cook for 1-2 minutes. Remove the sausages and leeks with a sieve spoon.
Melt the remaining clarified butter as well. Sweat potatoes in it for 3-4 minutes and deglaze with meat stock. Bring briefly to the boil and at medium. Let the heat simmer for about 15-20 minutes.
Lightly puree the stew with a hand blender. Pour in the cream, add the sausages and leeks again and season to taste. Take the stew off the fire.