Wash half a pound of nice, fresh mushrooms, peel them and cut off the
stems, cut the flaps into dice, and put the skins and stems in a
saucepan with a cup of water, and cook for ten minutes. While these are
cooking put a heaping tablespoonful of butter in a spider, when hot add
the mushroom dice and let them cook until tender, then add a
dessertspoonful of flour, and when it is cooked add the water the stems
were boiled in, and salt and pepper to taste. If the sauce is too thick
add a little more water. Stir in at the last a teaspoonful of finely
minced parsley, a few drops of lemon juice and the well-beaten yolk of
one egg, stir well, remove from the fire, fill the shells, sprinkle
bread crumbs over the tops and a little melted butter, put in the oven
for an instant to brown.