Serve with shredded lettuce and guacamole.
Melt butter in a large ovenproof skillet over medium heat; add rice mix, reserving seasoning packet. Stir in bell pepper and onion, and saute 6 minutes or until rice mix is lightly browned.
Stir in 2 1/4 cups water and seasoning packet. Bring to a boil; cover, reduce heat, and simmer 15 to 20 minutes or until rice is tender. Let stand 3 minutes. Stir in tomatoes and chicken.
Bake at 350° for 20 minutes; sprinkle with shredded cheese, and bake 5 more minutes or until thoroughly heated.
NOTE: For testing purposes only, we used Mexican Style Rice-A-Roni.