2 tablespoons olive oil
2 1/4 cups chopped onions
4 garlic cloves, minced
1 2 1/2-pound butternut squash, peeled, seeded, cut into 1-inch pieces
5 1/2 cups (or more) vegetable broth
3 teaspoons chopped fresh thyme
1/2 teaspoon grated orange peel
For Roasted Red Pepper Puree (optional):
1 cup coarsely chopped roasted red peppers
1 tablespoon extra-virgin olive oil
2 garlic cloves, chopped
1/4 teaspoon dried crushed red pepper
For Soup: Heat oil in heavy large pot over medium-high heat. Add onions; sauté until tender, about 12 minutes. Add garlic; stir 1 minute. Add squash and 5 1/2 cups broth; bring to boil. Reduce heat; cover and simmer until squash is soft, about 40 minutes. Cool slightly.
Working in batches, puree soup in blender until smooth. Return puree to pot. Add 1 teaspoon thyme and orange peel. Thin soup with more broth if desired. Simmer 3 minutes. Season with salt and pepper. (Can be made 1 day ahead. Cool slightly. Cover and chill. Rewarm before serving, thinning with more broth if desired.)
For Puree: Heat broiler or oven to at least 400. Slice two peppers in half lengthways and pull out the core, seeds, and stem. Place the pepper halves skin side up on a broiler pan or baking sheet. Place the peppers in the broiler or in the oven with the rack close to the heat source. Broil until the skin buckles and chars, about five to eight minutes. Cool, peel and chop. Puree all ingredients and season with salt and pepper to taste
Ladle soup into bowls. Swirl 1 tablespoon red pepper puree into soup in each bowl. Sprinkle with remaining 2 teaspoons thyme and serve.