With the rack in the lowest position, preheat the oven to 425°F (220°C).
In a 13 x 9-inch (33 x 23 cm) baking dish, combine the squash, onion and oil. Season with salt and pepper. Cook for 40 minutes.
Meanwhile, in a bowl, combine the cornstarch, broth and cream.
Arrange the cooked meatballs over the squash. Pour the broth mixture over the meatballs and squash. Bake for 10 minutes or until the sauce has thickened. Adjust the seasoning. Sprinkle with the parsley and cheese.