Preheat your oven to 400°F (200°C).
Cut the acorn squashes in half and remove the seeds. Brush the cut sides with olive oil and place them cut-side down on a baking sheet.
Roast the squashes in the preheated oven for about 30-35 minutes, or until they are tender and caramelized.
While the squashes are roasting, heat 1 tablespoon of olive oil in a soup pot over medium heat. Add the chopped onion and sauté until softened, about 5-7 minutes.
Stir in the minced garlic, cumin, cinnamon, and nutmeg, and cook for another 1-2 minutes until fragrant.
Once the squashes are done roasting, scoop out the flesh and add it to the soup pot along with the vegetable broth.
Bring the mixture to a simmer, cooking for an additional 5-10 minutes to allow the flavors to meld.
Using a blender or immersion blender, puree the soup until smooth. If you prefer a creamier texture, stir in the coconut milk or heavy cream.
Season the soup with salt and pepper to taste.
Ladle the soup into bowls and garnish with fresh parsley or chives, if desired.