Ingredients:

  • 2 large yellow onions, thinly sliced (approximately 400g/14 oz)
  • 2 tablespoons unsalted butter (30g/1 oz)
  • 1 tablespoon olive oil (15ml/0.5 fl oz)
  • 1/2 teaspoon granulated sugar (2.5g)
  • 1/4 teaspoon kosher salt (1.25g)
  • 1/4 cup beef broth or water (60ml/2 fl oz)
  • 1 pound (450g) ground beef (80/20 blend recommended)
  • 1 teaspoon Worcestershire sauce (5ml/0.17 fl oz)
  • 1/2 teaspoon garlic powder (2.5g)
  • 1/2 teaspoon onion powder (2.5g)
  • 1/2 teaspoon kosher salt (2.5g)
  • 1/4 teaspoon black pepper (1.25g)
  • 4 slices rye bread
  • 4 tablespoons unsalted butter, softened (60g/2 oz), divided
  • 4 slices Swiss cheese (or Gruyere for a fancier touch)
  • Optional: Thousand Island dressing or Russian dressing (for serving)

Instructions:

  1. Melt butter and olive oil in a skillet over medium-low heat. Add sliced onions, sugar, and salt. Cook, stirring occasionally, until onions are deeply golden brown and caramelized, about 25-30 minutes. Add beef broth or water during the last 5 minutes to deglaze the pan and help soften the onions.
  2. In a small bowl, gently combine ground beef, Worcestershire sauce, garlic powder, onion powder, salt, and pepper. Form into two equal-sized patties, slightly larger than the bread slices (they will shrink).
  3. Heat skillet over medium-high heat. Cook patties for 4-5 minutes per side for medium doneness, adjusting time based on your preference.
  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 slice with a slice of cheese, followed by a patty, caramelized onions, another slice of cheese, and finally the remaining slice of bread (butter-side up).
  5. Cook for 3-4 minutes per side, pressing down gently with a spatula, until the bread is golden brown and the cheese is melted and gooey.
  6. Slice in half and serve immediately.