Prep: 1. Peel, seed, and chop butternut squash into 2 inch chunks. 2. Finely chop sage. 3. Chop onion and garlic. Make: 1. Heat 1 tablespoon oil in a large skillet over medium heat. Add the sage, squash, onion, garlic and red pepper flakes to skillet. Season with salt and pepper. Cook, stirring occasionally, until onion is translucent, about 8 to 10 minutes. 2. Add broth and bring to a boil, then reduce heat and simmer until squash is soft, about 15 to 20 minutes. 3. In the meantime, bring water to a boil and cook the pasta according to package directions (Once pasta is done, drain and return to pot, reserving 1 cup cooking liquid) 4. Once the squash is soft let it cool slightly and then add to a blender. Purée the mixture until smooth (beware of hot steam escaping from the top of the blender), then season with salt and pepper to taste. 5. Combine squash purée and (if needed) about 1/4 cup pasta cooking liquid with pasta and heat, tossing and adding more pasta cooking liquid as needed, until sauce coats pasta. Season with salt and pepper if necessary.