Patty Melt Burger

Slice the onions thinly. In a bowl, season the ground beef with 0.5 tsp salt and 0.25 tsp black pepper. Form into four equal patties, slightly wider than your bread slices.

Melt 20g of butter in a large pan over medium-low heat. Add the sliced onions and cook slowly for about 20 minutes, stirring occasionally, until deeply caramelized and tender. Remove from the pan and set aside.

Increase the heat to medium-high. Add the beef patties to the same pan (or a separate one if needed) and cook for 3-5 minutes per side, or until desired doneness. Season with the remaining salt and pepper. Remove from pan.

Spread the remaining 30g of butter evenly on one side of each rye bread slice. Place four slices, butter-side down, in the pan. Top each with a cooked patty, a quarter of the caramelized onions, and 37.5g of Swiss cheese. Place the remaining four bread slices, butter-side up, on top. Grill for 2-3 minutes per side, pressing gently, until the bread is golden brown and the cheese is melted.

Slice each Patty Melt in half and serve immediately with mayonnaise and ketchup on the side.