From Cook's Country (part of America's Test Kitchen).
Instead of onions, which imparted a sharp taste to our Roasted Butternut Squash Soup, we switched to shallots, which had a sweeter, milder flavor. Rather than start the soup’s base of shallots and chicken broth on the stovetop, we cooked the two elements in the oven. We started by tossing chopped shallots with oil and the squash. Once the vegetables browned, we added a bit of broth to deglaze the roasting pan and popped it back in the oven to reduce the broth and concentrate the flavor. Only after pureeing the soup in the blender did we turn on the stove and heat everything through.
Because the bulbous end of butternut squash contains the seeds and stringy fibers, purchase squash with a relatively long neck—they have more usable flesh. You can replace the chicken broth with vegetable broth for a vegetarian version of this soup.
1 medium butternut squash (about 3 pounds), peeled, seeded, and cut into 1 1/2-inch chunks
1 1/2 pounds Golden Delicious apples, peeled, cored, and chopped
3 medium shallots, peeled and quartered
1/4 cup vegetable oil
Salt and pepper
4 cups low-sodium chicken broth (see note)
1 tablespoon maple syrup
1 teaspoon cider vinegar
1/8 teaspoon ground nutmeg
1/4 cup heavy cream
1. Adjust oven rack to middle position and heat oven to 450 degrees. Toss squash, apples, shallots, oil, 1 teaspoon salt, and ½ teaspoon pepper in large bowl, then arrange in single layer in large roasting pan. Roast, stirring occasionally, until vegetables are golden brown and softened, about 45 minutes. Add ½ cup broth to pan and scrape up any browned bits with wooden spoon. Return to oven and cook until liquid has reduced and vegetables are glazed, about 5 minutes.
2. Working in 2 batches, puree squash mixture and remaining broth in blender until smooth. Transfer pureed squash mixture to large saucepan and stir in syrup, vinegar, nutmeg, and cream. Bring soup to simmer over medium-low heat, adding ¼ cup water at a time as necessary to adjust consistency. Serve. (Soup can be refrigerated in airtight container for 3 days.)