This is how we make ours ...
Divide 1 lb hamburger (ground chuck for us) into 4 patties ... fry till desired doneness and set aside.
In the same skillet, saute 1 large onion, sliced thinly into rings, until nicely brown and sweet. How long you saute your onions depends wholey on how much time you have ... just get them soft if that's all the time you have. I get them really caramel'ly if I have the time. Remove onions from pan when done.
Butter the outsides of 8 slices of marble rye, place one patty, a pile of onions and slice of swiss cheese between 2 slices and fry / grill (in the same pany you've done everything else) like you would a grilled cheese sandwich.
Remove and enjoy when the bread is toasted to your liking.
I tend to use the same pan for everything because, IMHO, you get a better flavor from everything cooking together. Also, I'm not sure if cheese is traditional in a patty melt so you can leave that out if you want. Also, if you don't have marble rye, we've been known to use whatever is in the drawer ... white, caraway (spelling?), etc...