Heat oven to 350°F. Grease or spray 13×9-inch pan.
In large bowl, place 1 lb cooked and drained penne pasta, 2 cups shredded cooked chicken, 1 jar (15 oz) Alfredo pasta sauce and 1/2 cup ranch dressing. Stir to combine. Pour mixture in pan; spread evenly.
Sprinkled 6 slices chopped cooked bacon evenly over top, then sprinkle with 2 cups shredded mozzarella cheese (8 oz).
Bake 15 to 20 minutes or until hot and bubbly. Let stand 5 minutes before serving. Sprinkle with chopped parsley.