Wash and dry a bunch of kale raab, trim woody ends and rough chop. Set the oven to broil (~525F). Scatter raab on a baking sheet; drizzle with olive oil and sprinkle with salt and red pepper flakes. Toss with your hands or tongs to ensure everything is lightly coated. Roast for 3-5 minutes and watch to make sure that raab is browning, not burning. Pull from oven and top with parmesan and more pepper flakes, to taste.