In large saucepan, sauté onion and garlic in olive oil on medium heat for about 3 minutes, or until onions appear translucent. Add squash and sauté for a further 5 minutes. Add cinnamon, cumin, coriander, and salt and sauté for another minute before adding harissa. Stir frequently over next 2 minutes. Raise heat to high and add vegetable broth, stirring well. Bring to a boil, then reduce heat to gentle simmer and allow to cook for approximately 20 minutes, until squash is tender. Remove from heat and allow to cool slightly. Using hand mixer, blend soup into a fine purée.
