Preparation Cook broccoli in boiling salted water until crisp-tender but still bright green, about 5 minutes. Drain and cool. Cut florets lengthwise into 1/4-inch-thick slices. Coat large oval gratin or 13x9x2-inch glass baking dish with butter. Arrange broccoli slices, overlapping snugly, in rows in dish. Sprinkle with crushed red pepper, salt, and black pepper. Dot with 1/4 cup butter, then sprinkle with cheese. DO AHEAD: Can be made 8 hours ahead. Cover and chill. Preheat oven to 425°F. Bake gratinata uncovered until cheese is melted and broccoli tops brown, about 20 minutes.
Preparation Cook broccoli in boiling salted water until crisp-tender but still bright green, about 5 minutes. Drain and cool. Cut florets lengthwise into 1/4-inch-thick slices. Coat large oval gratin or 13x9x2-inch glass baking dish with butter. Arrange broccoli slices, overlapping snugly, in rows in dish. Sprinkle with crushed red pepper, salt, and black pepper. Dot with 1/4 cup butter, then sprinkle with cheese. DO AHEAD: Can be made 8 hours ahead. Cover and chill. Preheat oven to 425°F. Bake gratinata uncovered until cheese is melted and broccoli tops brown, about 20 minutes.