Prepare the Patties:

Divide the ground beef into 4 equal portions and shape them into patties. Season with salt and pepper.

Cook the Onions:

In a skillet over medium heat, melt 1 tablespoon of butter. Add the sliced onions and cook until they are golden brown and caramelized, about 10-15 minutes. Remove from the skillet and set aside.

Cook the Patties:

In the same skillet, cook the beef patties over medium-high heat until they are cooked to your desired level of doneness. Remove from the skillet and set aside.

Assemble the Patty Melts:

Spread butter on one side of each slice of Texas toast. Place a slice of American cheese on the unbuttered side of 4 slices of bread, followed by a cooked beef patty, caramelized onions, a slice of Monterey Jack cheese, and a drizzle of creamy pepper sauce (if using). Top with the remaining slices of bread, buttered side out.

Grill the Sandwiches:

In a skillet or griddle over medium heat, cook the sandwiches until the bread is golden brown and the cheese is melted, about 3-4 minutes per side.