Preheat your oven to 375°F (190°C).

Cut the squash in half and scoop out the seeds.

Drizzle a little bit of olive oil over the cut sides of the squash and season with salt and pepper.

Place the squash cut side down on a baking sheet lined with parchment paper.

Roast in the oven for 45 minutes, or until the squash is soft and easily pierced with a fork.

While the squash is roasting, prepare your other ingredients.

In a large pot, heat some olive oil over medium heat.

Add chopped shallots to the pot and sauté until translucent, about 3-4 minutes.

Add minced garlic and sauté for another 1-2 minutes.

Add chopped carrots, chestnuts, nutmeg, rosemary, black pepper, and a pinch of salt to the pot. Sauté for about 5 minutes or until vegetables are softened.

Once the squash is done roasting, scoop out the flesh and add it to the pot with the vegetables.

Pour in enough vegetable broth or hot water to cover all the ingredients.

Bring the soup to a boil, then reduce heat and let it simmer for 15-20 minutes.

Using an immersion blender, blend the soup until smooth and creamy.

Taste and adjust seasonings as needed.

Serve hot, garnished with a drizzle of olive oil and some fresh sage leaves.