Cut tortilla into very thin strips; place on a baking sheet. Bake at 325° for 10 minutes or until crisp. Set aside.
Coat a medium saucepan with cooking spray; add oil. Place over medium-high heat until hot. Add chicken; saute 4 minutes or until lightly browned. Add flour, and cook, stirring constantly, 1 minute. Gradually stir in tomato sauce, milk, and chicken broth. Stir in chili powder and next 4 ingredients. Cover, reduce heat, and simmer 15 minutes, stirring occasionally.
To serve, ladle soup into individual bowls, and top each serving with half of tortilla strips, 2 tablespoons tomato, 1 tablespoon cheese, and, if desired, 1/4 teaspoon jalapeno pepper.