5-ounce burger patties using 80/20 beef blend
Salt and freshly ground black pepper
slices Swiss cheese
slices seedless rye bread
cup caramelized onions (such as Caramelized Onions or your favorite recipe)
ounces (2 sticks) unsalted butter
Begin by seasoning the burgers with salt and pepper. Heat a saute pan over medium heat until hot. Sear off the burger patties to medium rare, 4 to 5 minutes per side. Transfer the patties to a sheet pan and cool to room temperature. Assemble the sandwiches with the Swiss cheese and Cheddar slices divided among half of the bread slices and the caramelized onions and beef patties divided among the other half of the slices. Combine 1 slice of each kind to create a sandwich. Heat a 12-inch skillet to medium and melt 4 tablespoons (2 ounces) of the butter into the pan per sandwich. Add in a sandwich and press with a steak weight or another pan to press all the ingredients together and warm and melt the cheese. Flip the sandwich and repeat until golden brown and the cheeses are melting. Repeat with each sandwich until complete. Cut in half and serve with salad or French fries.