Preheat oven to 300 degrees F.

Pat dry chuck roast and season on both sides with Kosher salt and ground black pepper.

In a Dutch oven, heat oil over medium-high heat and sear chuck roast on both sides until browned, about 5 minutes per side. Remove and set aside.

Reduce heat to medium, melt butter in the same pot, and add sliced onions. Cook for 25-30 minutes, stirring occasionally, until light brown.

Add minced garlic and cook for 2 minutes. Stir in white wine to deglaze and reduce by half. Sprinkle in flour and stir to coat.

Add beef broth, Worcestershire sauce, bay leaves, rosemary, and thyme. Bring to a simmer and season with salt and pepper.

Return the chuck roast to the pot, ensuring the liquid covers about ¾ of the beef. If necessary, add more broth.

Cover and braise in the oven for 3.5 hours until tender. Cook for an additional 20 minutes if desired.

Remove from oven, increase temperature to 400 degrees F.

Shred beef into smaller chunks, discarding excess fat, bay leaves, and herb bundles.

Top with shredded Gruyere cheese and return to the oven for 5-7 minutes until melted.

Serve warm over mashed potatoes or with baguette slices.