1/4 cup butter or margarine
2 large onions, thinly sliced
2 teaspoons minced fresh rosemary leaves
1/2 teaspoon salt
1/4 teaspoon coarsely-ground pepper
4 medium baking potatoes, thinly sliced
1 cup half-and-half
Heat butter in skillet until melted. Stir in onions, rosemary, salt and pepper. Cook over low heat, stirring frequently, until onion is very soft and begins to brown, about 20 minutes.
Arrange half of the potato slices in bottom of greased 10-inch pie plate. Top with half the onion mixture. Repeat layers. Pour half-and-half over the top. Cover with aluminum foil, and bake at 350 degrees F for 1 hour.
Uncover and bake until top is golden brown, about 20 minutes longer. Cut into wedges to serve.
Yields 6 to 8 servings.