2 1/2 cups heavy cream (NOT ultra-pasturized for best results)
3/4 cup finely chopped onions or shallots
2 teaspoons chopped fresh rosemary or 1 teaspoon dried
2 teaspoons sea salt
3/4 teaspoon ground black pepper
4 pounds Russet potatoes, peeled and cut into 1/4-inch rounds
2 cups packed grated sharp Cheddar or white Cheddar cheese
Preheat oven to 375 degrees. Butter a 13x9x2-inch glass baking dish.
In a medium bowl, whisk the cream, onions, rosemary, salt and pepper to blend.
Place half of the potato slices in prepared baking dish, overlapping slightly. Sprinkle with 3/4 cup of the cheese.
Top with second layer of potatoes. Pour cream mixture over potatoes. Sprinkle with remaining cheese.
Cover pan with foil and bake 1 hour. Uncover and bake until top is golden brown and potatoes are tender, another 45 minutes. Let cool 10 minutes before serving.