Broccoli-Parmesan Gratin

Preheat oven to 350 °F with rack in upper third. Cut broccoli florets into 1-inch pieces, then peel large stems with a knife and cut into 1/2-inch-thick rounds. Cook broccoli in boiling salted water (2 tablespoon salt for 6 qt water) 5 minutes, then drain. Meanwhile, whisk together milk, cream, cheese, eggs, and 1/2 teaspoon each of salt and pepper. Put broccoli in a 2-quart shallow flameproof baking dish, then pour milk mixture over top. Toss bread crumbs with oil and a pinch each of salt and pepper, then sprinkle evenly over gratin. Bake until custard is set, about 30 minutes. Turn on broiler, then broil until bread crumbs are golden brown, 2 to 3 minutes. Let stand 5 minutes.