01 - Preheat grill to medium-high, approximately 400°F.
02 - Combine potatoes, olive oil, rosemary, thyme, parsley, garlic, salt, and black pepper in a large mixing bowl. Toss until potatoes are evenly coated.
03 - Lay out two large sheets of heavy-duty aluminum foil. Divide seasoned potatoes evenly between the sheets and spread into a single layer. Fold foil over potatoes and tightly crimp edges to seal, forming two packets.
04 - Place foil packets on preheated grill. Grill for 20 to 25 minutes, turning once halfway through, until potatoes are fork-tender and lightly browned.
05 - Open foil packets carefully, watching for steam. Top with grated Parmesan cheese and additional chopped herbs if desired. Serve hot.