# What You'll Need:
→ Beef Patties
01 - 1.1 lbs ground beef (80/20 blend)
02 - 1/2 tsp salt
03 - 1/2 tsp black pepper
→ Caramelized Onions
04 - 2 large yellow onions, thinly sliced
05 - 2 tbsp unsalted butter
06 - 1 tsp sugar
→ Sandwich Assembly
07 - 8 slices rye bread or sourdough
08 - 8 slices Swiss cheese (or American cheese)
09 - 4 tbsp unsalted butter, softened
10 - 1 tbsp Dijon mustard (optional)
11 - 1 tbsp mayonnaise (optional)
# How to Make It:
01 - Melt 2 tbsp butter in a large skillet over medium-low heat. Add sliced onions and sugar. Cook, stirring frequently, until onions are deeply golden and caramelized, approximately 20-25 minutes. Remove from heat and set aside.
02 - While onions caramelize, season ground beef with salt and pepper. Form into 4 thin oval patties, matching the size and shape of your bread slices.
03 - Heat a separate skillet or grill pan over medium-high heat. Cook patties for 2-3 minutes per side until well-browned and cooked through. Remove from heat.
04 - Lay out 8 bread slices. Spread softened butter thinly on one side of each slice. Optionally, spread Dijon mustard or mayonnaise on the unbuttered side.
05 - On 4 bread slices (unbuttered side up), layer: one cheese slice, cooked beef patty, generous portion of caramelized onions, and another cheese slice. Top with remaining bread, buttered side facing outward.
06 - Heat a clean skillet or griddle over medium heat. Cook sandwiches for 2-3 minutes per side, pressing gently with a spatula, until bread is golden brown and cheese is fully melted.
07 - Remove sandwiches from heat and let rest for 1-2 minutes. Slice each sandwich in half diagonally and serve immediately while hot.
