Preheat the oven to 400 F.
Place butternut squash on a baking sheet, season with salt and pepper and drizzle with olive oil. Bake for 40 minutes or until tender.
Transfer butternut squash into a bowl of standing mixer, add 2 ladles of vegetable broth and process until smooth. Add more broth if needed.
Bring a large pot of salted water to boil. Add Penne and cook until ready, about 10-15 minutes. Drain, and set aside.
In a large saucepan, heat oil over medium heat. Add onion and cook until translucent, for 4 to 5 minutes. Add garlic and cook for 30 more seconds.
Add shiitake mushrooms and cook until soft, about 5 to 7 minutes.
Add sage and cook additional 2 to 3 minutes.
Stir in Crème Fraîche and butternut squash sauce.
Season with salt and pepper to taste.
Add cooked Penne and stir until fully coated in butternut squash sauce.
Sprinkle with Parmesan cheese if desired.