Preheat oven to 200°C (400°F). Toss diced squash, onion, carrot, and garlic with olive oil, salt, and pepper.
Roast vegetables for 25–30 minutes until tender and slightly caramelized.
Transfer vegetables to a large pot and add broth. Simmer gently for 10 minutes so flavors meld.
Blend until smooth using an immersion blender or transfer in batches to a countertop blender.
Stir in cream or coconut milk and season with nutmeg; taste and adjust salt as needed.
Serve hot, garnished with a drizzle of cream, toasted seeds, or fresh herbs.