In a Dutch oven, saute onion in oil and butter until tender. Add the garlic, cumin, cinnamon stick and chili powder; saute 1 minute longer.
Stir in the broth, squash, chickpeas, tomatoes, potatoes, lemon and salt. Bring to a boil. Reduce heat; cover and simmer for 15-20 minutes or until potatoes and squash are almost tender.
Add zucchini; return to a boil. Reduce heat; cover and simmer for 5-8 minutes or until vegetables are tender. Discard cinnamon stick and lemon slices. Stir in cilantro. Yield: 9 servings (about 2 quarts).