- Place the dried porcini mushrooms in water for approx. 15 minutes
- Place frozen peas in boiling water and cook for 3-5 minutes. Strain and reserve.
- Cook the potatoes with their skins in salted boiling water until tender.
- While the potatoes are still hot, remove the skins and put them through a potato ricer over a sauce pan
- Place the sauce pan back on the burner at low heat and stir in half the butter and milk until you obtain a smooth mixture
- Season with salt, pepper and a little nutmeg
- Remove the potatoes from the heat and add the parmesan cheese and the 3 eggs stirring generously (you do not want the eggs to coagulate). Reserve.
- In a large fry pan, melt the rest of the butter and sauté the sausage
- Add the dried porcini mushrooms which were strained and chopped and the regular mushrooms and sauté until the mushrooms are golden brown
- Add the tomato sauce and chopped parsley and season the mixture with salt and pepper. Let simmer for 10 minutes.
- Add peas and continue cooking for 2-3 minutes. Reserve and let cool slightly.
- Grease an 8×8 inch square casserole dish and sprinkle the breadcrumbs so that they stick to the entire mold. Eliminate the access.
- Place the sausage mixture in the casserole dish and top with the potato mixture.
- Brush the top with the egg yolk and sprinkle with some parmesan cheese and extra breadcrumbs.
- Place it in the oven at broil until the top is golden brown. Serve immediately!