1. Preheat oven to 425 degrees Fahrenheit. Place butternut squash flesh-side down on a cookie sheet lined with Gefen Parchment Paper. Roast in preheated oven until soft, 45 minutes to one hour, depending on size of squash.
2. Meanwhile, place head of garlic in the center of a piece of foil, cut-side up. Drizzle with olive oil, sprinkle with salt and wrap tightly in foil. Place in a small baking pan and roast in oven for 40 minutes. When squash and garlic are ready, remove from oven and let cool for a half hour.
3. Meanwhile, heat olive oil in large pot. Add onions and sauté until translucent, about seven minutes. Add sweet potato and parsnip and sauté for another five minutes. Next, scoop out the cooled butternut squash and add to pot. Unwrap garlic and squeeze the garlic out of the peels into the pot. Add broth and/or water to the pot (amount needed depends on how thick you want soup), and season with salt and pepper (and nutmeg, if desired). Cover and bring to a boil over medium-high heat, then lower to medium-low and cook for an hour or until vegetables are soft. Blend with a hand blender until smooth.
4. Garnish with crispy garlic croutons (see below) and serve.