Preheat oven to 425 degrees F.

Cut the squash in half lengthwise. Scoop out the seeds and discard them.

Place the squash on a baking sheet and spray with olive oil. Season with salt and pepper.

Remove the papery outside of the garlic. Cut 1/4 inch off the top of the garlic and add it to the baking sheet. Spray with olive oil, season with salt and pepper.

Cut the top and bottom of the onion off, then cut in half. Remove the papery outside and add to the baking sheet. Spray with olive oil and season with salt and pepper.

Roast the vegetables for 40 minutes, or until the butternut squash is soft.

Let the vegetables cool, then scoop out the butternut squash and add it to a blender. Also add the garlic, onion, nutmeg, salt, and pepper. Blend on high until the soup is creamy.