Boil potatoes until soft, add salt, butter, cow’s milk, nutmeg seasoning and egg yolk to make mashed potatoes and fold in the beaten egg white.
Cut the fennel lengthwise into 1 cm thick pieces and boil in a little tap water for ten minutes until soft.
Place in a baking dish, cut the sausage into 5 mm wide pieces and spread over the fennel. Pour the mashed potatoes over it and smooth it down, spreading it with a fork.
Bake in the oven at 200 degrees for about twenty to thirty minutes.
Serve with leaf salad.