1
Heat grill to medium-high heat. Lay 4 pieces of heavy duty aluminum foil on tray or cutting board. Wash and cut potatoes into slices, about 1/4 inch thick. Add onions and mushrooms (if desired) on top of potatoes Cut butter into pieces and add 1/2 tbsp of butter to each packet.
2
Cut butter into pieces and add 1/2 tbsp of butter to each packet. Combine the Italian seasoning, seasoning salt, and pepper. Sprinkle over the potatoes.
3
Close the packets, sealing them fully. Place on the grill and cook for 20-30 minutes until cooked through. Turn the packets and give them a few shakes during cooking.