Foil Pack French Dip Sandwiches

Name: Foil Pack French Dip Sandwiches
Prep time: 10 min
Cook time: 10 min
Total time: 20 min
Cuisine: American
Ingredients: 8 tablespoons unsalted butter (1/2 cup, softened to room temperature); 1 package au jus gravy mix (divided); 1 teaspoon Worcestershire sauce; 3/4 teaspoon dried minced garlic; 1/2 teaspoon onion powder; 1 long/large baguettes (or 2 smaller); 1 pound deli roast beef (ask for rare, since it’s getting cooked); 12 slices provolone cheese (1 pre-sliced package)