Make a thin white sauce with butter, flour, milk, and seasonings. Separate yolks from whites of eggs. Chop whites finely, and add them to the sauce. Cut four slices of toast in halves lengthwise. Arrange on platter, and pour over the sauce. Force the yolks through a potato ricer or strainer, sprinkling over the top. Garnish with parsley and remaining toast, cut in points.