Gather your ingredients including sourdough bread, roast beef, provolone cheese, butter, beef broth, Worcestershire sauce, garlic powder, salt, and pepper.

Warm the thinly sliced roast beef slightly in the microwave for about 30 seconds if desired.

Spread 1 tablespoon of softened butter on one side of each of the four slices of sourdough bread. On the unbuttered side, layer two slices of provolone cheese, followed by an even distribution of warm roast beef, and then another two slices of provolone cheese. Top with the remaining slices of bread, buttered side up.

Heat your skillet over medium heat and grill the sandwiches for about 3-4 minutes on each side until golden brown and the cheese is melted.

In a small saucepan, combine beef broth, Worcestershire sauce, garlic powder, salt, and pepper. Heat over low heat until warmed through.

Remove the sandwiches from the skillet, let them cool for a minute, slice in half, and serve with the warm au jus on the side.