Stir in second can of beans, green chilies, corn, carrot, celery, chicken broth, cumin, chili powder and salt, if desired; bring mixture to a simmer. Blend cornstarch into milk and stir into chowder; bring slowly to a boil, stirring frequently. Reduce heat and simmer 5 minutes, or until corn and celery are tender and mixture thickens. Stir in 1 cup of the cheese just until melted.