Preheat your oven to 400°F (200°C). Cut the butternut squash in half lengthwise, scoop out the seeds, and place it cut side down on a baking sheet. Roast for about 25 minutes or until tender.
While the squash is roasting, heat olive oil in a large pot over medium heat. Add the chopped onion and cook until softened, about 5 minutes.
Stir in the minced garlic, ground ginger, and cinnamon, cooking for another 2 minutes until fragrant.
Once the squash is roasted and cool enough to handle, scoop the flesh into the pot with the onions and garlic.
Add the vegetable broth and bring to a simmer. Simmer for about 10 minutes to combine the flavors, then remove the pot from heat.
Blend the soup using a blender or an immersion blender until smooth. Return to the pot if using a standard blender.
Season with salt and pepper to taste. If the soup is too thick, add a bit more broth or water to reach your desired consistency.
Serve hot, garnished with optional toppings as desired.