Quarter of an hour will suffice to prepare and cook this savory surprise, once the potatoes are baked. Take three large potatoes of symmetrical size, clean and bake them; cut each in two and remove the inside without injuring the skin. Melt half an ounce of butter by the fire, add two ounces of potato passed through a sieve, a teaspoonful of grated parmesan, pepper, salt, and a tablespoonful of milk. Then stir in the yolk of an egg and presently the white, well beaten. Fill the empty potato skins with the mixture which ought to rise and puff out in ten or twelve minutes.