Preheat grill to medium-high. Wash and scrub potatoes; prick all over with fork. Microwave on high, turning once, 8 to 10 min. until potatoes can be easily pierced with a fork. When cool enough to handle, cut each potato in half lengthwise. Scoop flesh into bowl, leaving 1/2-in./1-cm thick potato "shells".
Mash the scooped-out potato flesh with sour cream, salt and pepper. Stir 1/4 cup (60 mL) cheese, bacon and 4 tsp (20 mL) chives. Fill potato skins. Top with remaining cheese. Arrange on plank and place on grill. Close lid and cook 12 to 15 min.; or until cheese melts and potato is heated through. Garnish with remaining chives to serve.
For a vegetarian option, omit the bacon and stir in sautéed onions and mushrooms.
Substitute plain Greek yogourt for the sour cream.