Sauté onion and bell pepper in a Dutch oven coated with vegetable cooking spray over medium-high heat 3 to 4 minutes.
Stir in broth, tomatoes, and tomato paste.
Bring to a boil; reduce heat, and simmer 10 minutes.
Stir in cheese spread; cook 1 minute or until cheese spread is melted.
Stir in spaghetti and chicken, and cook 2 to 3 minutes or until thoroughly heated.