Heat olive oil in a large soup pot over medium heat. Add the onion and sauté until softened, about 5 minutes.
Add the cubed butternut squash and vegetable broth to the pot. Bring to a boil, then reduce the heat and simmer for about 20 minutes, or until the squash is tender.
Puree the soup using a blender or immersion blender until smooth. Stir in the nutmeg and cream (if using).
Serve hot, garnished with additional cream or roasted pumpkin seeds if desired.
Notes
This soup can be stored in the fridge for up to 3 days or frozen for later use. It's perfect for meal prep!