Step 1

Preheat oven to 350ºF. In a large shallow roasting pan, toss together squash, oil, 1 teaspoon salt, and 1/2 teaspoon pepper. Roast, uncovered, about 1 hour or until tender, stirring once.

Step 2

Meanwhile, in a 6- to 8-quart Dutch oven, cook onion in hot butter over medium-low heat about 20 minutes or until golden brown, stirring occasionally.

Step 3

Add roasted squash and broth. Bring to boiling; reduce heat. Simmer, uncovered, for 15 minutes. Cool slightly.

Step 4

Transfer squash mixture, in batches, to a blender; cover and blend until smooth. Return pureed mixture to Dutch oven. Season to taste with additional salt and pepper. If desired, garnish each serving with chives.