Heat olive oil in a large pot over medium heat.
Add diced onion and sauté until translucent.
Stir in minced garlic and cook for another minute.
Add cubed butternut squash and chopped carrots to the pot.
Pour in the vegetable broth and bring to a boil.
Reduce heat and let it simmer for 20 minutes, or until vegetables are tender.
Add thyme, nutmeg, salt, and pepper to the pot.
Use an immersion blender to purée the soup until smooth.
Taste and adjust seasoning if necessary.
Serve hot, garnished with pumpkin seeds if desired.