Preheat your oven to 300°F (150°C).

In a large skillet, heat the olive oil over medium-high heat. Season the beef chuck roast with salt and pepper, then sear it on all sides until browned, about 3-4 minutes per side.

Transfer the seared roast to a slow cooker. Add the sliced onion, minced garlic, beef broth, Italian seasoning, and red pepper flakes (if using). Cover and cook on low for 6-8 hours or until the beef is tender and easily shredded.

While the beef is cooking, prepare the roasted garlic aioli. In a small bowl, mash the roasted garlic cloves with a fork. Mix in the mayonnaise and lemon juice until smooth. Set aside.

Once the beef is done, shred it using two forks and mix it with the cooking juices in the slow cooker.

To assemble the sandwiches, place a generous portion of the shredded beef on each hoagie roll. Top with sliced provolone cheese.

Place the sandwiches on a baking sheet and broil in the oven for 2-3 minutes, or until the cheese is melted and bubbly.

Spread a layer of roasted garlic aioli on the top half of each roll, then close the sandwiches and serve immediately.