Tender French onion pot roast has all the classic flavors of French onion soup, including caramelized onions and a rich braising broth, and is served with crispy Gruyère baguette toasts.
Caramelize the onions. In a large Dutch oven over medium-low heat, add the sliced onions. Cook for 20-25 minutes, stirring occasionally and scraping up the browned bits from the bottom, until the onions are very soft and golden brown.
Don't rush this part too much—the caramelized onions are what will make it taste like French onion soup rather than simply beef with onions.
Add the garlic and cook for about 30 seconds. Set onions aside.
Season the roast. Pat the chuck roast dry and season all sides with salt and black pepper.
Sear the beef. Heat olive oil in a large Dutch oven over medium-high heat. Add the roast and sear for about 4-5 minutes per side, until deeply browned. Transfer the roast to a plate.
Deglaze with wine. Pour in the white wine. Scrape the bottom of the Dutch oven to loosen all the browned bits. Simmer for 3-4 minutes.
Build the broth. Stir in the beef broth and Worcestershire sauce. Return the chuck roast and onions to the Dutch oven. Add the fresh thyme and bay leaves.
Cover and bake. Bake at 325°F for 3-3 ½ hours, or until the roast is fork-tender and pulls apart easily. Remove the thyme stems and bay leaves. Keep covered and let the roast rest while making the Gruyère toasts.
Bake the cheese toasts. Increase the oven to 400°F. Arrange baguette slices in a single layer on a baking sheet. Drizzle with olive oil or melted butter. Sprinkle with garlic salt. Bake for 4 to 6 minutes, or until the bread is lightly crisp and golden around the edges. Remove the bread from the oven and sprinkle each slice with Gruyère cheese. Return the baguette slices to the oven and bake for 3 to 4 minutes, or until the cheese is melted and bubbly.
Serve. Shred the roast and spoon the onions over the top. Scoop bites with Gruyère toasts.