Heat oven to 425 degrees F. Cook potato slices in large pot of simmering salted water 8 to 10 minutes or until barely fork tender
Butter a 13 x 9 inch (3 quart) glass baking dish. In small bowl, stir together salt and 1/4 teaspoon of the pepper. Arrange one-fourth of the potato slices over bottom of dish; sprinkle with one-fourth of the salt mixture. Cover with second layer of potatoes; sprinkle with one-fourth of the salt mixture. Top with onions and artichokes. Repeat layering of potatoes and sprinkling of salt mixture twice.
In medium bowl, whisk together cream, creme fraiche, nutmeg and remaining 1/8 teaspoon pepper, pour over gratin. Bake 15 minutes.
Meanwhile, in small bowl, stir together cheese and bread crumbs. After 15 minutes of baking, sprinkle gratin with cheese mixture; dot with butter. Bake an additional 20 to 25 minutes or until golden brown and bubbling.