Place pinto beans in a food processor; process until smooth.
Spoon bean puree into a large Dutch oven. Add chicken and next 4 ingredients; stir well. Cook over medium heat 15 minutes or until thoroughly heated.
Ladle soup into bowls; top each with about 3 tablespoons cheese. Serve with low-fat tortilla chips, if desired (chips not included in analysis).
Tip: If you need to reduce the amount of sodium in this recipe, use 1 (14 1/2-ounce) can no-salt-added tomatoes.