Cut the eggs in halves lengthwise.
Remove the yolks and pass through a sieve.
Place the whites in a serving dish.
Prepare the duxelle by cooking the chopped shallot in the butter without coloring, add the well-washed and finely chopped mushroom or mushroom trimmings, cook for 3-4 min.
Mix the yolks with the duxelle and correct the seasoning.
Spoon or pipe the mixture into the egg white halves.
Cover the eggs with mornay sauce, sprinkle with grated parmesan cheese and brown slowly under a salamander or on the top of a moderate oven.
Place the dish on a flat and serve.