In a nonstick Dutch oven coated with cooking spray, saute sweet potatoes and onion in oil until crisp-tender. Add the chili powder, garlic, cumin and cayenne; cook 1 minute longer. Stir in the beans, tomatoes, coffee, honey, salt and pepper., Bring to a boil. Reduce heat; cover and simmer for 30-35 minutes or until sweet potatoes are tender. Sprinkle with cheese.