Boil the eggs quite hard; clear away the shells, cut them in half, take out the yolks, and put the whites into warm water. Pound the yolks in a mortar till they become very fine. Have ready some parsley and a little onion chopped as fine as possible; add these to the yolks, with a pinch of salt and cayenne pepper. Add a sufficient quantity of hot cream to make it into a thick even paste; fill the halves of the whites with this, and keep the whole in hot water. Prepare white sauce; place the eggs on a dish in two rows, the broad part downward; pour the sauce over them, and serve up hot.