Preheat your home oven to 400°F (200°C).
Toss the cubed butternut squash in olive oil, salt, and pepper. Spread them evenly on a baking sheet and roast in the oven for about 25-30 minutes or until golden brown and tender.
In a large pot, sauté the onion and garlic in olive oil until translucent.
Add the roasted butternut squash to the heated pot and stir to combine.
Pour in the chicken or vegetable broth and bring to a quick boil. Reduce the heat to a simmer and let the soup cook for 10-15 minutes or until the squash is very soft.
Puree the soup until soft using a regular blender, and puree the soup until smooth.
Stir in the heavy cream, cinnamon, nutmeg, salt, and pepper. Let the soup simmer for another 12 minutes.
Adjust seasonings to taste and serve hot. If desired, you can top the soup with croutons, chopped parsley, or a drizzle of olive oil.