Preheat oven to 350 degrees F. On top of stove, cook macaroni as directed on box. Wash chicken breast and let drain in colander. Cut chicken into bite size pieces. Heat the olive oil and add the chicken pieces to skillet and saute until no longer pink.
Drain macaroni and set aside. Add chicken soup to chicken in skillet, stir well. Mix in Ro*Tel tomatoes stirring well. Drain diced tomatoes and add to mixture, add in macaroni and mix all ingredients together well.
Pour into a large casserole dish that has been sprayed with non-stick cooking spray or lightly greased with oil. Cover casserole loosely with foil.
Bake for 30 to 35 minutes or until bubbly. Remove from oven and sprinkle with Mexican style cheese, return to oven uncovered to melt cheese. Remove casserole from oven and let stand 5 minutes before serving.