Microwave 8 cups broccoli florets, covered, until just tender, 8 minutes; transfer to a small baking dish. Melt 2 tablespoons butter in a saucepan over medium heat. Add 4 teaspoons flour; cook, whisking, until smooth, 2 minutes. Add 1 1/4 cups milk; season with salt, black pepper and cayenne. Cook, whisking, until thickened, 8 to 10 minutes. Whisk in 2 tablespoons grated pecorino romano. Pour over the broccoli and toss; top with more pecorino. Broil until browned.