Patty Melt - cooking recipe

Ingredients

1 slice American cheese
1 slice swiss cheese
1/4 lb ground beef
1/4 cup onions, sliced or 1/4 cup onion, diced
3 tablespoons butter, divided
2 slices rye bread

Preparation

Saute onions until golden in 2 tablespoons butter until translucent and lightly golden.
Remove from the pan.
Form the meat patty so it will fit the bread.
Grill to desired doneness.
Butter bread on one side; put buttered side down on hot griddle, put 1 slice cheese followed by onions then cooked patty, followed by cheese.
Butter one side of the other slice of bread and place on top buttered side out.
Fry until bread is crisp but not burned (I have trouble with this part), turn over and do the same thing on the other side. Cheese should be well melted.
Slice on the diagonal.