Slice the onion as thinly as possible and set aside. Slice the potato as thinly as possible and set aside. Get a heavy oven proof pan or skillet. I used my iron skillet. Put the oil in the skillet and swirl it around so that the bottom and sides are well covered. You can use a pastry brush to do this as well. Put a layer of potatoes. Put them in a daisy pattern, larger pieces covering the outside, smaller in the inside. Put some of the onion slices on top of the potatoes. Put more potatoes on top of the first layer, and sprinkle very lightly with seasoned salt. Continue doing this until you have used up all the potatoes and onions. Melt the butter, and drizzle it over the layers. Place in a preheated 350 oven, cover and bake for 20 minutes. Remove cover and bake for another 15 or so minute, or until the potatoes are golden. Enjoy!