Since planks are made of wood they will catch fire. Please use caution and follow these tips when planking. Always use water soaked planks before grilling. Use untreated western red cedar planks. Have a fire extinguisher at the ready. Never leave your grill when planking. Periodically check that the plank is not on fire. In the event of flames, reduce burner temperature, open lid, douse the fire with a squeeze bottle of water, close lid and continue planking. Be aware of the wind direction when planking. Never open grill lid into the wind. Stand with your back to the wind when opening the grill to avoid the smoke from getting in your eyes. Do not use planks more than once. Allow planks to fully cool before discarding. Use a large bucket of cold water to cool the planks after cooking.
Preheat grill to high (about 500°F).
In a bowl combine spinach, cream cheese, cubed bread, Mozzarella cheese, lobster meat, red onion and garlic. Season with 1 tbsp. barbecue seasoning and mix well. Set aside.
Season snook with remaining 1 tbsp. barbecue seasoning, gently pressing the spices into the fish to adhere.
Place seasoned snook on plank, tucking the tail underneath the body of the fish so it wont burn on the grill.
Mound the spinach and lobster mixture onto planked snook and lay sliced prosciutto over top.
Carefully place plank onto grill, close lid and plank-bake snook for 15 to 20 minutes, checking occasionally that fish is not burning, until snook flakes easily with a fork and cheese is melted and all is heated through.
Carefully remove planked snook from grill, slice into 4 and serve immediately.