Preheat the oven to 350 degrees F (175 degrees C).

In a medium saucepan over medium heat, combine the beef consommé, Worcestershire sauce, garlic powder, and thyme if using. Bring to a simmer.

Add the sliced roast beef to the simmering broth and cook for about 3-4 minutes until heated through.

While the beef is warming, lightly butter the inside of each hoagie roll.

Using tongs, remove the beef from the broth and divide it equally among the bottom halves of the rolls.

Top each sandwich with 2 slices of provolone cheese.

Place the sandwiches open-faced on a baking sheet and toast in the preheated oven for 3-5 minutes, until the cheese is melted and the bread is lightly toasted.

Close the sandwiches with the top halves of the rolls.

Strain the remaining broth into small bowls for dipping.

Serve the sandwiches hot with individual bowls of au jus on the side.