Caramelized Onion Patty Melt
A classic diner-style patty melt featuring a juicy, seasoned beef patty, sweet and savory caramelized onions, and gooey melted Swiss cheese, all toasted to crispy perfection between slices of buttery rye bread.
Equipment
- Large skillet (preferably cast iron)
- Medium skillet or griddle
- Spatula
- Mixing bowls
Ingredients
Caramelized Onions
- 2 medium Yellow onions — Thinly sliced
- 1 tablespoon Unsalted butter
- 1 tablespoon Olive oil
- 0.25 teaspoon Kosher salt
- 1 teaspoon Balsamic vinegar (optional) — To deglaze
Patties
- 0.75 pound Ground beef (80/20) — Divided into two equal portions
- 1 teaspoon Worcestershire sauce
- 0.5 teaspoon Kosher salt
- 0.5 teaspoon Black pepper — Freshly ground
Melt Sauce
- 2 tablespoons Mayonnaise
- 1 tablespoon Ketchup
- 1 tablespoon Sweet pickle relish
Assembly
- 4 slices Rye bread — Thick cut if possible
- 4 slices Swiss cheese
- 2 tablespoons Unsalted butter — Softened, for spreading on bread
Caramelized Onions
| 2 medium | Yellow onions | Thinly sliced |
| 1 tablespoon | Unsalted butter | |
| 1 tablespoon | Olive oil | |
| 0.25 teaspoon | Kosher salt | |
| 1 teaspoon | Balsamic vinegar (opt.) | To deglaze |
Patties
| 0.75 pound | Ground beef (80/20) | Divided into two equal portions |
| 1 teaspoon | Worcestershire sauce | |
| 0.5 teaspoon | Kosher salt | |
| 0.5 teaspoon | Black pepper | Freshly ground |
Melt Sauce
| 2 tablespoons | Mayonnaise | |
| 1 tablespoon | Ketchup | |
| 1 tablespoon | Sweet pickle relish |
Assembly
| 4 slices | Rye bread | Thick cut if possible |
| 4 slices | Swiss cheese | |
| 2 tablespoons | Unsalted butter | Softened, for spreading on bread |
Instructions
-
In a large skillet over medium-low heat, melt 1 tablespoon of butter with the olive oil. Add the sliced onions and salt. Cook slowly, stirring occasionally, until the onions are deep golden brown and very soft, about 30-35 minutes. If they start to dry out, add a splash of water. Stir in the balsamic vinegar at the end to deglaze the pan. Remove from pan and set aside.
~35 minPatience is key for caramelized onions; do not turn up the heat to rush them or they will burn instead of sweeten. -
While the onions cook, mix the mayonnaise, ketchup, and sweet pickle relish in a small bowl to create the melt sauce. Set aside.
~5 min -
Form the ground beef into two oval-shaped patties roughly the same shape as your rye bread. Make them slightly larger than the bread as they will shrink while cooking. Gently press a shallow dimple in the center of each. Season both sides with salt, pepper, and Worcestershire sauce.
~5 minThe dimple prevents the patty from puffing up into a ball while cooking. -
Heat a cast iron skillet over medium-high heat. Cook the patties for 3-4 minutes per side until a nice crust forms and they are cooked to your desired doneness. Transfer to a plate to rest.
~8 minWipe out the excess grease from the skillet if you plan to use the same pan to toast the sandwiches. -
Butter one side of each slice of rye bread. Place two slices, butter-side down, on a cutting board. Spread the melt sauce on the unbuttered sides. Top each with a slice of Swiss cheese, a cooked beef patty, a generous scoop of caramelized onions, another slice of Swiss cheese, and the top slice of bread (butter-side up).
~3 minLayering cheese on both sides of the meat helps to glue the sandwich together as it melts. -
Heat a clean skillet or griddle over medium-low heat. Place the assembled sandwiches in the pan and cook until the bread is golden brown and crispy, about 3-4 minutes. Carefully flip and cook for another 3-4 minutes on the other side until the cheese is completely melted.
~8 minIf the bread is browning too fast before the cheese melts, cover the skillet with a lid for a minute to trap the heat. -
Remove the patty melts from the skillet and let them rest for a minute before slicing in half. Serve hot.
~1 min
Tips & Storage
- You can make the caramelized onions and the sauce up to 3 days in advance and store them in the fridge to speed up this recipe for a weeknight dinner.
- For an extra punch of flavor, use a mix of Swiss and sharp cheddar cheese.
- Press down gently on the sandwich with a spatula or a bacon press while toasting to ensure even browning and melting.
- Storage: Patty melts are best enjoyed fresh, but leftovers can be wrapped tightly in foil and stored in the refrigerator for up to 2 days. Reheat in a skillet over low heat or in an air fryer to recrisp the bread.