Pre-heat oven to 450 degree and line a baking sheet with foil. Spray with cooking spray.
In a large bowl, toss together broccoli with olive oil, salt and pepper. Spread in an even layer on baking sheet and roast until golden brown and caramelized, about 20 minutes.
While broccoli is still warm and fresh from the oven, toss with parmesan cheese and chili flakes. Serve warm.