Preheat oven to 425°F with rack in upper third position. Toss squash with 1 tablespoon oil and ¼ teaspoon pepper on a large rimmed baking sheet until well coated; spread in an even layer. Roast, stirring once, until tender, about 30 minutes. Leaving the squash in the oven, increase oven temperature to broil. Broil until browned, about 2 minutes. Let cool slightly on the baking sheet, about 5 minutes.