Ingredients:

  • 2 tablespoons butter, unsalted (30 ml)
  • 2 large yellow onions, thinly sliced (about 400g)
  • 1 teaspoon sugar (5g)
  • 1/4 teaspoon salt (1.5g)
  • 1/4 cup beef broth (60 ml)
  • 1 pound (454g) ground beef, 80/20 blend recommended
  • 1 teaspoon kosher salt (5g)
  • 1/2 teaspoon black pepper (2.5g)
  • 1 tablespoon Worcestershire sauce (15 ml)
  • 4 slices rye bread
  • 4 tablespoons butter, softened (60g)
  • 4 slices Swiss cheese

Instructions:

  1. Melt butter in skillet. Add onions, sugar, and salt. Cook over medium-low heat, stirring occasionally, until deeply golden brown and caramelized (about 20 minutes). Add beef broth to deglaze the pan and scrape up any browned bits. Set aside.
  2. Gently combine ground beef, salt, pepper, and Worcestershire sauce in a bowl. Form into two equally sized patties (use a burger press for even cooking if you have one).
  3. Heat skillet over medium-high heat. Cook patties for 3-4 minutes per side for medium-rare, or longer to desired doneness (internal temperature of 160°F for medium).
  4. Spread softened butter on one side of each slice of rye bread. Place two slices of bread, butter-side down, in the skillet. Top each with a slice of Swiss cheese, a cooked patty, caramelized onions, another slice of Swiss cheese, and the remaining slice of bread, butter-side up.
  5. Cook for 3-4 minutes per side, or until golden brown and the cheese is melted and gooey. Press down with a spatula to ensure even cooking. Cut in half and serve immediately.