1 package (1 oz.) ranch dressing mix
1 cup canned pineapple juice
2 tablespoon olive oil
1 tablespoon balsamic vinegar
1 tablespoon soy sauce
6 boneless, skinless chicken breasts
6 slice fresh pineapple
6 slice sharp white Cheddar cheese

To make the marinade, whisk together first 5 ingredients in a small bowl. Place chicken breasts in a gallon-size zip-top bag; pour marinade into bag and seal; shake bag several times to coat chicken evenly. Refrigerate for at least 1 hour or overnight. Preheat grill to medium-high. When grill is hot, discard marinade and grill chicken breasts 5 to 6 minutes per side, until juices run clear and chicken is cooked through; grill pineapple 2 to 3 minutes per side. Top each chicken breast with one slice of cheese; cover and grill 1 to 2 minutes more until melted. Serve each chicken breast topped with a slice of grilled pineapple.