Lay a layer of potatoes on top of the butter a layer of chopped onion then sprinkle with the seasoning salt Repeat until all potatoes onion and seasoning salt is gone
Put the rest of the butter on top of the potatoes evenly
Fold the edges of the aluminum foil together and seal
Twist the end of the foil to prevent butter from leaking out
Take second piece of foil and cover the bundle for the second time