Mashed potatoes must be cold, so ideally prepare them the day before serving. Place potatoes into a large pot and cover potatoes with cold water. Bring water to a boil, add salt and boil until tender (about 5-10 minutes). Drain well and set aside for 10 to 15 minutes to dry out.
Mash potatoes together with the butter, chopped herbs and season with salt and pepper to taste. Take care not to over mash, potatoes should be slightly lumpy.
Set potatoes aside to cool at room temperature. When cooled, cover and refrigerate overnight.
Preheat grill to high heat.
Spray mushrooms and sliced onions with non-stick cooking spray and season with Napoleon® Classic Steak Spice to taste. Grill vegetables for 5-6 minutes or until lightly charred and tender. Remove from grill and allow to cool slightly. Thinly slice mushrooms and onions and place into a large mixing bowl. Add cheese curds and Parmesan cheese, mix well and season with salt and coarsely ground black pepper to taste. Cover and set aside until needed.
Season steaks with Napoleon® Classic Steak Spice, pressing seasoning into the meat.
Place steaks onto grill and sear for 2 to 3 minutes on one side only. Remove from grill and evenly space steaks, seared side facing up, onto a 2’ long Napoleon® Cedar Plank.
Reduce grill temperature to medium heat.
Form the chilled potatoes around the steaks into uniform-level mounds surrounding each steak, leaving the tops of the steaks exposed. Place plank onto
Grill and close the lid. Plank grill steak and potatoes for 15-20 minutes, until potatoes are golden brown, crisp and heated through.
Remove the plank from the grill. Top each steak with ¼ of the mushroom and onion mixture, so that steak is completely covered. Return plank to grill and cook for an additional 8-10 minutes, or until cheese is completely melted and bubbling.
Carefully remove the smoking plank from the grill and place onto a heat resistant surface, or another soaked plank. Serve immediately.