As soon as my mom tasted it, she rushed over to get the recipe from me.

Roll out the ground beef into thin patties and divide into four equal parts. Give each side a good seasoning of salt and pepper.
Patties should be fried for about 3 to 4 minutes on each side over medium-high heat in the same skillet. After taking it out of the pan, put it aside.
Spread butter on one side of each rye bread piece. On a pristine griddle or pan set over medium heat, lay four slices butter-side down.
Layer cooked patties, caramelized onions, Swiss cheese, cheddar cheese, and butter-side up bread on top of each piece of bread.
Melt the cheese and toast the bread for two to three minutes on each side.
Take the patties out of the pan after they’re done cooking and set them aside to cool for a minute before cutting them in half. Quickly serve with the secret sauce drizzled or served on the side.
Tips and Variations
Substitute ground chicken or turkey with the beef for a leaner alternative. You may customize it to your taste by combining other cheeses; for example, pepper jack can provide a spicy bite. A plant-based burger patty is a great alternative for vegetarians. The secret sauce is the star ingredient in this dish, so be sure not to leave it out.