Pat the chuck roast dry with paper towels. Drizzle oil on each side and liberally season with salt and pepper.
Heat a skillet to medium-high heat and sear roast on each sides until a crust forms. Remove and place in a crockpot.
Thinly slice onions and add to the crockpot along with the broth, soy sauce, Worcestershire, and seasonings. Cover and cook on low for 8 hours or high for 4 hours. Roast should be fall apart tender & onions caramelized.
For extra crispy bread, bake the baguette for roughly 7-10 minutes at 350 degrees before slicing. Then slice and remove some of the bread from the top half. Place on a baking sheet, slather with mayonnaise (optional), add lots of roast onto bottom half, some of the caramelized onions and cheese. Bake until cheese is melted & gooey. Sandwich together, cut & serve with au jus.
To make au jus, strain some of the broth from crockpot.
