2 tablespoons vegetable oil
1 pound skinless, boneless chicken breast halves
1/2 cup finely chopped onion
1 cup finely chopped green bell pepper
1 cup grated Parmesan cheese
1 cup shredded mozzarella cheese
1 cup shredded Cheddar cheese
Heat oil in a large skillet over medium heat. Add chicken and onion; simmer for 5 minutes, stirring. Cook 5 minutes longer. Remove chicken; place in skillet. Cook 5 minutes longer, stirring. Pour oil into skillet; heat through.
Return chicken to skillet; add cheese, mozzarella cheese, Cheddar cheese, and chicken; mix well. Pour over chicken and onion mixture.