This roasted cauliflower dish gets an upgrade with a delicate melted Parmesan topping, and whole roasted garlic cloves.
Preheat oven to 425 degrees. Mix the cauliflower, onion, and garlic in olive oil; place on a large-rimmed baking sheet with rosemary sprigs. Roast, tossing occasionally, until almost tender, around 35-40 minutes. Sprinkle with Parmesan, toss to combine, and roast until cauliflower is tender, 10 minutes longer.