1. Heat oven to 450 degrees with two racks centered. Spray two 12-by-14-inch roasting or jelly-roll pans with cooking spray. Arrange onions, rutabaga, turnips, carrots, squash, and brussels sprouts evenly in the two pans. Drizzle all with 1 tablespoon olive oil, and toss lightly to coat vegetables. Sprinkle each pan with 1/2 teaspoon salt and 1/4 teaspoon pepper. Sprinkle rosemary and thyme evenly over each pan, and roast for 25 minutes; turn vegetables with a spatula for even browning. Cook until vegetables are tender when pierced with a knife, 15 to 25 minutes more. Brussels sprouts may cook faster than other vegetables; if so, transfer to a serving platter, and keep warm until remaining vegetables are tender.