The moment my mom tried it, she couldn't wait to snag the recipe from me!

Servings: 4

1 pound ground beef
1 large onion, sliced
8 slices rye bread
4 slices Swiss cheese
4 slices cheddar cheese
2 tablespoons butter
Salt and pepper to taste
1/2 cup mayonnaise
2 tablespoons ketchup
2 tablespoons sweet pickle relish
1 teaspoon Worcestershire sauce

Start by making the secret sauce. In a small bowl, combine mayonnaise, ketchup, sweet pickle relish, and Worcestershire sauce. Mix well and set aside.

In a large skillet, melt butter over medium heat. Add sliced onions and cook until caramelized, about 15 minutes.

Divide ground beef into 4 portions, shape into patties, and season with salt and pepper.

Cook patties in the skillet until done, about 4-5 minutes per side.

Butter one side of each rye bread slice. Place 4 slices, buttered side down, on a skillet over medium heat.

Layer each with a slice of Swiss cheese, a cooked patty, caramelized onions, and a slice of cheddar cheese.

Top with another slice of rye bread, buttered side up.

Cook until the bread is golden brown and the cheese is melted, about 3-4 minutes per side.