Reduce heat to medium; add a little more olive oil, the red onions and garlic to pot. Cook about 5 minutes, stirring occasionally, until onions are softened. Stir in jalapeño chiles; cook about 2 minutes or until softened. Stir in chili powder. Stir in tomatoes. Heat to a simmer over medium heat, then stir in broth and cooked chicken. Reduce heat to medium-low. Simmer uncovered about 45 minutes or until chicken is wonderfully tender.