Pat the chuck roast dry with paper towels and season it generously with salt and pepper.

In a large skillet over medium-high heat, add a tablespoon of oil and brown the roast on all sides for about 4-5 minutes per side.

Remove the roast from the skillet and set aside. In the same skillet, add another tablespoon of oil if needed and cook sliced onions for about 10-15 minutes, stirring often until golden and caramelized.

Transfer the caramelized onions to the slow cooker and place the beef roast on top. Add minced garlic, beef broth, and the French onion soup mix.

Cover and set the slow cooker on low for 8-10 hours or high for 4-5 hours until the beef is fork-tender.

Once cooked, shred the beef lightly with two forks or serve in thick slices.

Ladle some of the cooking liquid over the beef before serving.