Step 1: Prepare the Au Jus

• In a medium saucepan, heat the butter over medium heat until melted.
• Add the garlic powder, onion powder, black pepper, and thyme, stirring for about 30 seconds until fragrant.
• Pour in the beef broth, Worcestershire sauce, soy sauce, and bay leaf. Stir to combine.
• Bring the mixture to a gentle simmer and let it cook for about 10 minutes, allowing the flavors to meld together.
• Remove the bay leaf and thyme sprig, then keep warm on low heat while preparing the sandwiches.

Step 2: Toast the Bread

• Preheat your oven to 375°F (190°C).
• Spread a thin layer of butter on the inside of each French roll or baguette.
• Place the bread halves on a baking sheet, cut side up, and toast for 5-7 minutes, or until golden and crispy.

Step 3: Warm the Roast Beef

• If using pre-cooked deli roast beef, place the slices in the warm au jus for about 1-2 minutes to heat through without overcooking.
• If using homemade roast beef, slice it thinly against the grain and briefly dip each slice in the au jus before assembling.

Step 4: Assemble the Sandwiches

• Place a generous portion of warm roast beef onto the bottom half of each toasted roll.
• If using cheese, place a slice on top of the beef and return the sandwiches to the oven for 2-3 minutes, just until the cheese melts.
• Place the top halves of the rolls over the beef, pressing gently to secure the filling.

Step 5: Serve with Au Jus

• Pour the warm au jus into small dipping bowls for each serving.
• Serve the sandwiches immediately, dipping each bite into the flavorful broth for the ultimate French Dip experience.