Season & Sear Beef: Pat the beef chuck roast completely dry with paper towels. Season all sides generously with kosher salt, black pepper, garlic powder, and onion powder. Heat olive oil in a large heavy skillet over medium-high heat until shimmering. Sear the chuck roast for 4 to 5 minutes per side until a deep, caramelized golden-brown crust forms. (Do not skip this step—it builds tremendous foundation flavor for your au jus!).

Assemble in Slow Cooker: Scatter sliced onions and smashed garlic cloves across the bottom of a 6-quart slow cooker. Transfer the seared chuck roast on top of the onions. Pour in the beef broth, French onion soup, Worcestershire sauce, and soy sauce around the sides of the beef. Tuck in the fresh thyme, rosemary sprigs, and bay leaves.

Slow Cook to Tender Perfection: Cover with the lid and cook on LOW for 8 to 9 hours (or on HIGH for 4 to 5 hours) until the beef is fall-apart tender and yields effortlessly to the gentle pull of a fork.

Shred Beef & Prepare Au Jus: Transfer the cooked roast to a large rimmed cutting board or bowl. Use two forks to shred the beef into succulent bite-sized strands, discarding any large excess pieces of fat. Strain the slow-cooker braising liquid through a fine-mesh sieve into a bowl to remove herbs, onion solids, and bay leaves. Skim off any excess surface oil with a ladle or fat separator. Taste the au jus and season with a pinch of salt and pepper if needed. Toss a ladle of warm au jus back over the shredded beef to keep it exceptionally moist.

Toast Garlic Hoagie Rolls: Preheat your oven broiler to HIGH. Mix softened butter, 1/2 tsp garlic powder, and parsley together in a small bowl. Spread evenly onto the cut sides of the hoagie rolls. Arrange rolls open-faced on a baking sheet and broil for 2 to 3 minutes until lightly golden and crisp.

Melt Cheese & Assemble: Heap generous mounds of warm shredded beef onto the bottom halves of the toasted rolls. Top each sandwich with two slices of provolone cheese. Return under the broiler for 1 to 2 minutes until the cheese is completely melted, bubbly, and slightly browned at the edges.

Serve with Warm Au Jus: Close the sandwiches, slice each in half diagonally, and serve immediately alongside individual ramekins of hot, steaming savory au jus for dipping!