1Brush olive oil over chicken breasts. Heat coals or gas grill for direct heat.
2Place chicken on grill rack; cover and grill over medium heat 4 minutes, turning once until there are grill marks on both sides of chicken.
3In large skillet, place partially cooked chicken. Add tomatoes, spinach and oregano leaves; cover and cook over low heat about 10 to 12 minutes, or until juice of chicken is no longer pink when center of thicket pieces are cut and spinach is wilted.
4Sprinkle with salt and pepper to taste. Place chicken breasts on serving platter; spoon tomato mixture with spinach over chicken. Sprinkle cheese over top (the carry-over heat will melt it nicely). Sprinkle fresh basil over top for garnish.