Preheat oven to 400 degrees. Line two rimmed baking sheets or shallow roasting pans with parchment paper. In a large bowl, toss squash, apples, onion, garlic, and ginger until mixed well. Spread mixture on a baking sheet in a single layer. Roast squash mixture until tender and beginning to brown, about 45 to 50 minutes, rotating pans between oven racks halfway through baking.
Remove from oven and puree squash mixture with broth, 1 cup water and nutritional yeast in a blender or food processor in 2 batches until smooth.
Transfer to a medium saucepan and bring to a simmer over medium heat. Add more water if needed to thin soup to desired consistency. Serve garnished with parsley.
Recipe from http://www.wholefoodsmarket.com/recipes/3090.