1. Preheat the oven to 400°F.

2. Peel the butternut squash, remove the seeds, and cut it into medium chunks.

3. Slice the top off the head of garlic to expose the cloves.

4. Place the squash on a parchment-lined baking sheet, drizzle with olive oil, and season with salt and black pepper.

5. Wrap the garlic in foil with a small drizzle of olive oil.

6. Roast the squash and garlic for 35 to 45 minutes, turning the squash once halfway through, until the squash is tender and the garlic is soft.

7. Transfer the roasted squash to a large bowl or food processor.

8. Squeeze the roasted garlic cloves out of their skins and add them to the squash.

9. Add the butter, heavy cream, thyme, and Parmesan cheese if using.

10. Mash with a potato masher or blend until smooth and creamy.

11. Taste and adjust seasoning if needed.

12. Serve warm with extra butter, thyme, or black pepper on top if desired.