Preheat oven to 350 degrees.Scrub and slice potatoes. (I use a mandoline for an even slice.)Prepare foil. Use heavy duty foil if you have it. Otherwise use a double layer. Cut off a piece large enough to fold over potatoes on all sides. Spray evenly with non-stick cooking spray.Mix potatoes with ranch dressing. Layer on foil. Top with bacon, shredded cheese, salt pepper and parsley.With heat on medium, grill for about 15 minutes. Flip over and grill for another 15-20 minutes or until potatoes are fork tender.