Via Schott’s Food & Drink Miscellany, “a curious exhibition recipe sadly long out-of-fashion”:
Break a dozen or two of eggs and separate the whites from the yolks. Tie the yolks in a pig’s bladder, boil them hard, and remove them. In a larger pig’s bladder, place the whites. Into the midst of the whites, place the set yolks and tie the bladder tight. Boil the whole until the whites harden and then remove from the water. Serve the Monster Egg on a bed of spinach.
Just wanted to share that. In case you wanted to bring it back in fashion.