Gruyere Potato Gratin

1 pound large red potatoes
3/4 cup coarsely grated Gruyere cheese (about 3 ounces)
1 large egg
1 cup milk, heated just to boiling
Kosher salt
Freshly ground black pepper.

Preheat oven to 400 degrees and butter a 1 1/2 quart gratin or shallow baking dish.

Bring a large saucepan of salted water to a boil. Peel potatoes and cut into thin slices (about 1/8 inch thick). Add potatoes to boiling water and parcook 4 minutes. Drain potatoes well in a colander.

In gratin or baking dish, arrange potatoes, overlapping them, in 3 layers. Sprinkle the first two layers each with 1/4 cup Gruyere and salt and pepper.

In a small bowl, whisk egg and add hot milk in a stream, whisking. Season mixture with salt and pepper and pour evenly over potatoes. Sprinkle potatoes with remaining 1/4 cup cheese and bake for 30 minutes or until top is golden and potatoes are tender.

Makes 2 generous servings. (For our dinner party, I tripled the recipe.)