Preheat oven to 375F.
Slice potatoes into 1/4 inch thick slices.
Place potatoes in a greased 8-in. square baking dish.
In a bowl, beat the egg. Add in the cream, salt, nutmeg and pepper and mix well.
Pour mixture over the potatoes. Sprinkle with cheese.
Bake, uncovered, for 40-45 minutes or until the potatoes are tender. Serve warm with additional cheese or fresh thyme sprinkled on top.