Elegant Butternut Squash Soup
["2 butternut squash (about 2 lb. each)", "2 qt. chicken broth", "2 Tbsp. unsalted butter", "1 Tbsp. olive oil", "1 medium-sized onion, chopped", "1/2 tsp. ground mace", "1/2 tsp. ground ginger", "1 Tbsp. light brown sugar", "salt and freshly ground black pepper to taste", "truffle oil (for garnish)", "about 1/3 c. freshly grated Parmesan cheese"]
["Halve the squash lengthwise; peel, seed and cut into chunks. Place in a soup pot with the broth. Simmer, partially covered, until tender, 20 to 25 minutes. Transfer the squash to a bowl with a slotted spoon; reserve broth. Melt the butter in the oil in a nonstick skillet over very low heat. Add the onion and cook, stirring, until wilted, about 15 minutes. Sprinkle with the mace and ginger. Cook, stirring, for 1 minute more. Add the cooked onion mixture and the brown sugar to the squash and stir well. Season with salt and pepper."]
["butternut squash", "chicken broth", "unsalted butter", "olive oil", "onion", "ground mace", "ground ginger", "light brown sugar", "salt", "truffle oil", "Parmesan cheese"]