Preheat the oven to 400°F (200°C). Place the halved butternut squash on a baking sheet, drizzle with olive oil, and season with salt and pepper. Roast in the oven for about 40-45 minutes, or until the flesh is tender and caramelized.

While the squash is roasting, heat a large pot over medium heat. Add a little olive oil, then sauté the diced onion until translucent, about 5-7 minutes. Add the minced garlic and cook for an additional minute until fragrant.

Once the squash is done roasting, scoop the flesh into the pot with the onions and garlic. Pour in the vegetable broth and add the cinnamon and nutmeg. Bring to a simmer and cook for about 10 minutes to allow the flavors to meld.

Using an immersion blender, puree the soup until smooth. If you don’t have an immersion blender, carefully transfer the soup in batches to a blender.

Stir in the heavy cream and maple syrup (if using). Heat the soup gently until warmed through, then taste and adjust seasoning as needed.

Serve hot, garnished with fresh sage leaves if desired.