Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.

Place the butternut squash halves (flesh side up), quartered onion, and garlic bulb on the baking sheet. Drizzle everything generously with olive oil and season with salt and pepper.

Roast in the oven for 40-45 minutes, or until the squash is completely tender when pierced with a fork and the onions are slightly caramelized.

Once cool enough to handle, scoop the butternut squash flesh out of the skin and transfer it to a large dutch oven or soup pot over medium heat. Squeeze the roasted garlic cloves out of their skins into the pot, and add the roasted onions.

Pour the vegetable broth into the pot. Add the fresh thyme, salt, pepper, and ground nutmeg. Bring to a gentle simmer.

Using an immersion blender, blend the soup directly in the pot until it is completely velvety and smooth. (Alternatively, carefully transfer to a standing blender in batches).

Turn the heat to low, stir in the heavy cream, and let it warm through for 2 minutes. Do not let it boil after adding the cream.

Ladle into warm bowls, garnish with an extra swirl of cream and toasted pumpkin seeds, and serve immediately with crusty bread.