Ultimate Patty Melt with Secret Sauce

Ingredients:1 lb ground beef8 slices of rye bread8 slices of Swiss cheese1 large onion, thinly sliced4 tbsp butter, plus more for spreadingSalt and pepper to tasteFor the Secret Sauce:1/2 cup mayonnaise2 tbsp ketchup1 tbsp relish1 tsp Worcestershire sauce1/2 tsp garlic powder1/2 tsp onion powderSalt and pepper to tasteDirections:Begin by mixing the secret sauce ingredients in a small bowl. Adjust seasoning to taste, then set aside.In a skillet over medium heat, melt 1 tbsp of butter. Add the thinly sliced onions, season with salt and pepper, and cook until caramelized, about 10-15 minutes. Transfer to a plate.Form the ground beef into 4 patties, slightly larger than your bread slices. Season both sides with salt and pepper.In the same skillet, cook the patties to your desired doneness, about 4 minutes per side for medium. Remove and set aside.Butter one side of each bread slice. To assemble, spread the secret sauce on the non-buttered side of 4 slices, add a slice of cheese, a patty, caramelized onions, another slice of cheese, and top with another bread slice, buttered side up.In a clean skillet over medium heat, grill the sandwiches until golden brown and the cheese is melted, about 3-4 minutes per side.Prep Time: 15 minutes | Cooking Time: 30 minutes | Total Time: 45 minutesKcal: 650 kcal | Servings: 4 servings