In a 6-qt. stockpot, heat oil over medium-high heat; saute onion until tender, 4-6 minutes. Stir in spices. Add potatoes, chickpeas, stock and water; bring to a boil. Reduce heat; simmer, covered, until potatoes are tender, 15-20 minutes., Puree soup using an immersion blender. Or cool slightly and puree soup in batches in a blender; return to pan and heat through. Top with bacon, green onions and, if desired, cheese.Freeze option: Freeze cooled soup in freezer containers. To use, partially thaw in refrigerator overnight. Heat through in a saucepan, stirring occasionally and adding a little stock or water if necessary.