Preheat oven to 425 degrees. Line a rimmed baking sheet with aluminum foil.
In a large bowl combine broccoli florets and garlic, then drizzle with olive oil. Toss to coat broccoli evenly with olive oil. Sprinkle in salt, pepper and red pepper flakes (if using) and toss to combine.
Spread broccoli florets evenly onto the prepared baking sheet. Roast for 10 minutes, stir broccoli then roast for an additional 5 to 10 minutes, until edges are browned and broccoli is crispy.