# What You'll Need:
→ Beef
01 - 1 lb ground beef (80/20 blend)
02 - 1/2 tsp kosher salt
03 - 1/2 tsp black pepper
04 - 1/2 tsp Worcestershire sauce
→ Onions
05 - 2 large yellow onions, thinly sliced
06 - 2 tbsp unsalted butter
07 - 1 tbsp olive oil
08 - Pinch of salt
→ Bread & Cheese
09 - 8 slices rye bread
10 - 8 slices Swiss cheese
→ Assembly
11 - 3 tbsp unsalted butter, softened
# How To Make It:
01 - In a large skillet over medium-low heat, melt 2 tbsp butter with olive oil. Add sliced onions and a pinch of salt. Cook, stirring occasionally, until deeply caramelized, about 20 minutes. Set aside.
02 - Season ground beef with salt, pepper, and Worcestershire sauce. Shape into 4 oval patties slightly larger than bread slices.
03 - Heat cast-iron skillet over medium-high heat. Cook patties for 3 to 4 minutes per side until browned and cooked through. Transfer to a plate.
04 - Wipe skillet clean. Spread softened butter on one side of each bread slice.
05 - Place one bread slice, buttered side down, in skillet. Layer with slice of cheese, beef patty, caramelized onions, another slice of cheese, and top with second bread slice, buttered side up.
06 - Cook over medium heat until bread is golden brown and cheese melts, about 3 to 4 minutes per side. Press gently with spatula to brown evenly.
07 - Slice melts in half and serve immediately while hot.
