Preparation Preheat oven to 375°F. Toss shallots with 1 tablespoon oil and roast in a shallow baking pan in lower third of oven 25 minutes. Toss together squash, bell peppers, sweet potatoes, salt, cumin, coriander, cinnamon, and remaining 3 tablespoons oil. Add roasted shallots and divide between 2 large shallow (1-inch-deep) baking pans. Dot vegetables in each pan with half of butter and roast in upper and lower thirds of oven, stirring occasionally and switching position of pans halfway through roasting, until vegetables are tender, about 45 minutes total. Cooks' note:Vegetables may be roasted 1 day ahead, then cooled before chilling, covered. Reheat in a 350°F oven until hot, 15 to 20 minutes.
Preparation Preheat oven to 375°F. Toss shallots with 1 tablespoon oil and roast in a shallow baking pan in lower third of oven 25 minutes. Toss together squash, bell peppers, sweet potatoes, salt, cumin, coriander, cinnamon, and remaining 3 tablespoons oil. Add roasted shallots and divide between 2 large shallow (1-inch-deep) baking pans. Dot vegetables in each pan with half of butter and roast in upper and lower thirds of oven, stirring occasionally and switching position of pans halfway through roasting, until vegetables are tender, about 45 minutes total. Cooks' note:Vegetables may be roasted 1 day ahead, then cooled before chilling, covered. Reheat in a 350°F oven until hot, 15 to 20 minutes.