Cook rice according to package instructions, cook 5 minutes less than the specified time.
Cut chicken into bite-sized pieces. Sauté chicken with onion and butter until chicken is fully cooked, stirring as needed. Lightly season with salt and pepper.
In a small bowl, combine cream of chicken soup, sour cream, chicken broth, salt and pepper. Mix.
Add the cooked rice, chicken, soup mixture, broccoli florets, tomatoes, red pepper and 1/3 of the grated cheese to a casserole dish. Mix well to combine. Add remaining cheese over top of casserole. Sprinkle bread crumbs over cheese.
Cover casserole with foil, bake 20 minutes. Remove foil, bake another 15-20 minutes until ingredients bubble and cheese melts and is golden in color.