Begin by patting the beef chuck roast dry with paper towels to remove excess moisture. Season it generously with salt and pepper on all sides.

In a large skillet, heat olive oil over medium-high heat until shimmering. Carefully add the roast and sear for about 3-4 minutes on each side until golden-brown.

Once the roast is beautifully browned, remove it from the skillet and place it in the slow cooker.

In the same skillet, sauté the onion for 2-3 minutes until softened, then add the garlic and cook for an additional minute until fragrant.

Pour the sautéed onion and garlic mixture over the roast in the slow cooker.

Layer the carrots and potatoes around the roast in the slow cooker. If using mushrooms, add them now.

In a separate bowl, whisk together beef broth, Worcestershire sauce, dried thyme, dried rosemary, and bay leaves.

Pour the prepared broth mixture over the roast and vegetables in the slow cooker.

Cover the slow cooker and set it to cook on low for 8-10 hours, or on high for 4-5 hours.

Once cooking time is complete, carefully remove the roast and vegetables from the slow cooker and let the roast rest for 10 minutes before slicing.