Preheat oven to 400°F (200°C).

Cut butternut squash in half, scoop out seeds, and place cut-side up on a baking sheet. Roast for 30-40 minutes, or until tender.

While squash is roasting, heat olive oil in a large pot over medium heat. Add onion and cook until softened, about 5 minutes. Add garlic and cook for 1 minute more.

Add crushed tomatoes, vegetable broth, cinnamon, and nutmeg to the pot. Bring to a simmer.

Once squash is roasted, scoop out the flesh and add it to the pot. Simmer for 10-15 minutes, allowing flavors to meld.

Use an immersion blender or transfer to a regular blender to blend until smooth. Season with salt and pepper to taste.

Serve hot.