The patty melt is a traditional cheeseburger with caramelized onions on sliced rye bread that's been enjoyed since the 40's.
Cut onion in half and then slice.
Mix ground beef with Worcestershire sauce, salt and pepper. Form into 4 patties and set aside.
Butter both sides of your bread slices.
Melt 2 tablespoons of butter in a skillet at med-low heat. Add onion. Cook for about 20-25 min stirring occasionally until softened and browned.
While onions are cooking, place a large skillet over medium heat. Toast bread in the pan on both sides.
In the large skillet, melt 2 tablespoons of butter at medium heat. Cook burgers for about 3-4 min on one side and flip. Continue cooking until done (140F for medium) usually another 3-5 minutes.
Once nearly done add cheese to burger. Cover to melt.
Stack up your burgers and enjoy!