Bring a large pot of water to a boil; cook pasta according to package directions.
Meanwhile, in a 12-inch skillet sauté onion with olive oil until translucent (about 3-4 minutes).
Add butternut squash and sauté three minutes. Stir in vegetable broth and bring to simmer, cook thoroughly (about ten minutes).
Cool the sauce down and process ½ of the sauce in a blender until smooth, combine with the diced butternut squash.
Meanwhile, in a small skillet heat butter until it turns light brown, add sage and Brussels sprouts and sauté until caramelized and thoroughly cooked, season with salt and pepper. Set aside.
Drain pasta and toss with butternut squash sauce.
Serve topped with Brussel sprouts and [optional] cheese.
