1Wash the squash. Using a chef's knife, carefully cut off the bottom and stem ends of the squash. Cut the narrow part (neck) from the rounded bottom part of the squash; cut the rounded bottom in half. Using a spoon, scoop out the seeds and fibers from the bottom halves and discard. Using a sharp vegetable peeler, remove the peel from the neck and 2 bottom halves. Cut squash into 1-inch pieces.
2Scrub the potatoes thoroughly with a vegetable brush and water to remove any dirt, but do not peel. Cut each potato into eighths. Peel the onion; cut into 16 wedges and separate pieces. Peel the sweet potato and cut into 1-inch pieces. Peel and finely chop the garlic.
3Heat the oven to 425°F. Spray a 15x10x1-inch pan with the cooking spray. Place the squash, potatoes, onion, sweet potato and carrots in the pan. Pour the oil over the vegetables. Sprinkle with the garlic, sage, rosemary and salt. Stir to coat vegetables.
4Roast uncovered 35 to 45 minutes, stirring occasionally, until vegetables are crisp-tender when pierced with a fork.