Quick Recipe Version (TL;DR)
Quick Ingredients
- 3 lb beef chuck roast
- 2 1/2 tsp kosher salt, 1 tsp black pepper
- 3 tbsp unsalted butter + 1 tbsp olive oil
- 4 large yellow onions (about 3 lb), thinly sliced
- 4 cloves garlic, minced
- 1 lb cremini mushrooms, halved or thickly sliced
- 3 cups low-sodium beef broth
- 2 tbsp Worcestershire sauce
- 8 sprigs fresh thyme (or 1 1/2 tsp dried), 2 bay leaves
- 1/3 cup dry sherry or dry white wine (optional but recommended)
- 2 tbsp cornstarch + 2 tbsp cold water (slurry)
- 1 tsp sherry vinegar or lemon juice (optional finish)
- For toasts: 1 small baguette (12 slices), 2 tbsp butter or olive oil, 6 oz Gruyère, shredded
Do This
- 1) Pat roast dry; season with salt and pepper. Sear 4–5 min per side in 1 tbsp oil until deeply browned.
- 2) In same pan, cook onions in 3 tbsp butter with a pinch of salt, stirring occasionally, 18–22 min until caramelized; add garlic 1 min.
- 3) Deglaze with sherry (optional), scrape browned bits; add 1 cup broth and Worcestershire; simmer 1 min.
- 4) In slow cooker: mushrooms on bottom, half the onions, roast, then remaining onions. Add thyme, bay, remaining broth and pan juices. Cook LOW 8–9 hr (or HIGH 4.5–5.5 hr) until fork-tender.
- 5) Make Gruyère toasts: Bake baguette at 450°F for 5 min, top with cheese, broil 1–2 min until bubbly.
- 6) Rest roast 10 min. Skim fat; whisk in cornstarch slurry; cook on HIGH 10–15 min until glossy. Adjust salt; finish with 1 tsp vinegar or lemon (optional). Serve with toasts.
Why You’ll Love This Recipe
- All the cozy flavors of French onion soup meet fall-apart tender pot roast.
- Slow cooker convenience with stovetop caramelized-onion depth.
- Rich mushroom-onion gravy you’ll want to eat by the spoonful.
- Gruyère-topped toasts for dunking make it feel restaurant special.
Grocery List
- Produce: Yellow onions (4 large), garlic (4 cloves), cremini mushrooms (1 lb), fresh thyme, parsley or chives (optional), lemon (optional)
- Dairy: Unsalted butter, Gruyère cheese (6 oz)
- Pantry: Beef chuck roast (3 lb), low-sodium beef broth (3 cups), Worcestershire sauce, dry sherry or white wine (optional), cornstarch, olive oil, kosher salt, black pepper, bay leaves, baguette
Full Ingredients
For the Pot Roast and Gravy
- 3 lb beef chuck roast
- 2 1/2 tsp kosher salt, divided
- 1 tsp freshly ground black pepper
- 1 tbsp olive oil
- 3 tbsp unsalted butter
- 4 large yellow onions (about 3 lb), halved and thinly sliced
- 4 cloves garlic, minced
- 1 lb cremini mushrooms, cleaned and halved or thickly sliced
- 3 cups low-sodium beef broth
- 2 tbsp Worcestershire sauce
- 1/3 cup dry sherry or dry white wine (optional but adds classic French onion flavor)
- 8 fresh thyme sprigs (or 1 1/2 tsp dried thyme)
- 2 bay leaves
To Thicken and Finish
- 2 tbsp cornstarch mixed with 2 tbsp cold water (slurry)
- 1 tsp sherry vinegar or lemon juice (optional, to brighten)
- Additional salt and pepper to taste
- 2 tbsp chopped fresh parsley or chives (optional garnish)
For the Gruyère Toasts
- 1 small baguette, cut into 12 slices (1/2 inch thick)
- 2 tbsp melted unsalted butter or olive oil, for brushing
- 6 oz Gruyère cheese, finely shredded
Step-by-Step Instructions
Step 1: Prep the roast and onions
Pat the beef chuck roast very dry with paper towels. Season all over with 2 tsp kosher salt and 1 tsp black pepper. Halve and thinly slice the onions; mince the garlic. Set a large heavy skillet over medium-high heat.
Step 2: Sear the beef
Add 1 tbsp olive oil to the hot skillet. Sear the roast until deeply browned, 4–5 minutes per side. Transfer the beef to a plate. Do not clean the pan; those browned bits are flavor.
Step 3: Caramelize the onions
Reduce heat to medium. Add 3 tbsp butter to the skillet, then the onions and 1/2 tsp kosher salt. Cook, stirring every couple of minutes, until the onions are soft, jammy, and golden brown, 18–22 minutes. Stir in the garlic and cook 1 minute more until fragrant.
Step 4: Deglaze and build the broth
Pour in the dry sherry (if using) and scrape up the fond with a wooden spoon; simmer 1 minute to reduce slightly. Stir in the Worcestershire and 1 cup of the beef broth; bring to a simmer for 1 minute. This becomes your flavorful cooking liquid.
Step 5: Load the slow cooker and cook low and slow
Place the mushrooms in the bottom of a 5- to 7-quart slow cooker. Spoon in half of the caramelized onions. Nestle the seared roast on top, then cover with the remaining onions. Tuck in the thyme sprigs and bay leaves. Pour in the skillet liquid and the remaining 2 cups beef broth. Cover and cook on LOW for 8–9 hours (or on HIGH for 4 1/2–5 1/2 hours), until the meat is fork-tender and pulls apart easily. For a temperature guide, the roast will typically read 195–205°F when perfectly tender.
Step 6: Make the Gruyère toasts
About 15 minutes before serving, heat the oven to 450°F. Arrange baguette slices on a baking sheet and brush both sides lightly with melted butter or olive oil. Bake 5 minutes until lightly crisp. Top each slice with shredded Gruyère and broil 1–2 minutes until the cheese is melted and bubbling with browned spots. Set aside.
Step 7: Finish and thicken the gravy
Transfer the roast to a board and tent with foil to rest for 10 minutes. Fish out and discard the thyme stems and bay leaves. Skim excess fat from the surface of the cooking liquid. Whisk in the cornstarch slurry. Set the slow cooker to HIGH and cook, stirring occasionally, until the gravy is glossy and lightly thickened, 10–15 minutes. Taste and adjust seasoning with salt and pepper; add 1 tsp sherry vinegar or a squeeze of lemon to brighten if you like.
Step 8: Serve
Slice or gently pull the beef into large chunks. Spoon the onions, mushrooms, and plenty of gravy over the meat. Garnish with chopped parsley or chives. Serve hot with the Gruyère toasts for dunking.
Pro Tips
- Caramelize fully. Deeply golden onions are the backbone of French onion flavor—do not rush this step.
- Keep the lid closed. Every peek at the slow cooker adds 20–30 minutes to the cook time.
- Degrease for silkier gravy. Use a ladle or fat separator before thickening.
- Shred vs. slice. If the roast is ultra-tender, pull it into large pieces instead of thin slices to soak up more gravy.
- Gruyère matters. Finely shred the cheese so it melts quickly into those classic bubbly, browned spots.
Variations
- Instant Pot: Sear and sauté onions on Sauté mode; pressure cook 60 minutes on High with natural release 15 minutes. Thicken on Sauté.
- Mushroom swap: Mix cremini with shiitake or oyster mushrooms for extra savoriness.
- Gluten-free: Skip the toasts and serve with mashed potatoes or polenta; the roast and gravy are naturally gluten-free when thickened with cornstarch.
Storage & Make-Ahead
Refrigerate cooled roast and gravy (and extra toasts stored separately) in airtight containers for up to 4 days. The flavors deepen by day two. Freeze the meat and gravy up to 3 months; thaw overnight in the fridge and reheat gently on the stovetop or in a 300°F oven until hot. Make the onions a day ahead to save time; store chilled and proceed with the recipe.
Nutrition (per serving)
Approximate per serving (1/6 of roast, gravy, and two Gruyère toasts): 780 calories; 49 g protein; 43 g fat; 64 g carbohydrates; 5 g fiber; 10 g sugars; 1180 mg sodium.
