Add the baconĀ to a large skillet (cast iron is best) over low heat. Cook until bacon is crispy and browned. Remove the bacon and pour off the bacon grease, but reserve it for later.
Wipe out the pan and return it to medium heat. Shape the ground beef into two thin four ounce patties. Season them well with salt and pepper. Add a drizzle of oil to the skillet and cook the patties for 4 minutes per side, or until they are cooked through.
Meanwhile, stir together the chopped cooked bacon with Swiss cheese (you can either cube it or grate it).
When patties are cooked remove them from the skillet and wipe out the skillet again. Return it to medium heat.
Brush the bread with reserved bacon grease on one side. Add two slices of bread, greased side down, to the skillet. Drizzle the bread with mustard and add the cooked beef patty. Then top with a generous handful of the Swiss and bacon mixture. Top with a second piece of bread, greased side up.
Cook the patty melt for about 3 minutes per side over medium low heat until bread is browned and cheese is well melted. Serve immediately!