Preheat the oven to 400 degrees. On a large baking sheet add the chopped butternut squash, sweet potato, and carrot. Drizzle with olive oil and toss the veggies to make sure they are all coated with oil. Season with salt and pepper. Roast in the oven for 40-45 minutes. Stirring every 15 minutes or so. Remove the veggies from the oven and set aside.
In a large soup pot, add the olive oil. Add in the onion. Cook until tender. Add the garlic and cook for 2 minutes.
Stir in the roasted veggies. Cook for five minutes.
Add in the vegetable broth and water. Add the cinnamon, nutmeg, and salt and pepper. Stir.
Let the soup cook for 20 minutes.
Puree the soup with a hand held blender. If you don't have one, transfer soup to a blender and puree in batches.