Wash the scallops and set aside.
Gently cook the whole potatoes in their skins in the duck fat for 90 minutes over low heat. Set aside.
Cook the eggs using a Roner thermostat or in steam for 90 minutes at 144 degrees F.
Brown the scallops on both sides in a skillet and leave to stand for 1 minute. Peel the potatoes and cut with a pasta-cutter to form discs 1.2" in diameter. Season with salt and pepper and dip in the grated truffle.
Shell the eggs and separate the yolks from the whites. Cut the yolk, which will be very creamy, in half. Use a fork to break up and lightly beat the whites which will be shaky. Season with salt and pepper and add the truffle.
To form the millefeuille, layer the scallop, the egg yolk and the potato dipped in truffle, then repeat. Serve accompanied with the egg whites and the truffle.