1 pound lean ground beef
1 teaspoon Worcestershire sauce
1 teaspoon minced fresh rosemary
1/8 teaspoon black pepper
Kosher salt, to taste
4 slices swiss cheese
1/4 cup mayonnaise
4 sesame seed buns
Toppings (suggested toppings include caramelized onions, sautéed mushrooms, or sliced tomatoes)
In a large bowl, combine the beef, Worcestershire, rosemary, and black pepper. Mix until everything is well combined.
Divide the beef into 4 large patties. Form them into circles and push your finger through the center, creating a doughnut.
Heat a large cast iron skillet over medium-high heat. Season each patty with kosher salt, to taste, and place it on the hot skillet.
Cook the burgers for 8-10 minutes, flipping once, until they are cooked through. If you're using a meat thermometer, look for 140 degrees F for medium and 160 degrees F for well done.
When the burgers are almost fully cooked (about 5 degrees F off from the final cooking temperature), place the swiss cheese on top of each patty. Place a lid on top of the cast iron skillet until the cheese is melted.
Spread 1 tablespoon of the mayonnaise on the bottom of each bun. Top each bun with the burger patty and the toppings of your choice.