Preheat oven to 400°F (200°C). Toss butternut squash cubes with 1 tablespoon olive oil, salt, and pepper on a baking sheet.
Roast squash for 35-40 minutes, turning once halfway through, until tender and lightly caramelized.
While squash roasts, heat remaining olive oil in a large pot over medium heat. Add onion and cook for 5 minutes until softened.
Add garlic and chopped apple, cooking for 2-3 minutes until fragrant.
Add roasted squash, vegetable broth, cinnamon, and nutmeg to the pot. Bring to a boil, then reduce heat and simmer for 10 minutes.
Using an immersion blender, puree soup until completely smooth and creamy. You can also use a regular blender, working in batches.
Stir in heavy cream and maple syrup. Heat through for 2-3 minutes without boiling.
Taste and adjust seasonings as needed. Serve hot, garnished with toasted pumpkin seeds and a drizzle of cream if desired.