1. Preheat oven to 500°. Place peppers in a single layer on an aluminum foil-lined baking sheet, and bake 10 minutes on each side or until peppers are blistered. Place peppers in a large zip-top plastic freezer bag; seal and let stand 10 minutes to loosen skins. Peel peppers; remove and discard seeds. Coarsely chop peppers, and place in a 6-qt. slow cooker.
2. Add tomatoes and next 5 ingredients. Cover and cook on LOW 6 to 7 hours. Skim fat from top of soup. Remove chicken, using a slotted spoon, and shred. Return chicken to soup, and add salt to taste.
Note: We tested with Swanson 100% Natural Mexican Tortilla Flavor Infused Broth.