Adjust oven rack to lowest position and heat oven to 500 degrees Spray a large (18- by 12-inch) rimmed baking sheet with vegetable cooking spray. Add cauliflower, olive oil, and spices; toss to coat. Place in the oven and roast until cauliflower is cooked through and impressively colored, about 20 minutes for fresh cauliflower and 25 minutes for frozen.