chicken cobbler recipe

2 cups cooked chicken, shredded (you can use rotisserie chicken for convenience) 1 cup frozen mixed vegetables (peas, carrots, corn, green beans) 1/2 cup chopped onion 1/2 cup chopped celery 1/2 cup chopped bell pepper 2 tablespoons butter 1/4 cup all-purpose flour 2 cups chicken broth 1/2 cup milk 1 teaspoon garlic powder