Pat the chuck roast dry with paper towels. Season generously with salt and pepper.
Heat olive oil in a large skillet over medium-high heat. Sear the roast on all sides until browned (~3-4 minutes per side).
In the crockpot, add chopped onion, carrots, and celery to create a flavorful base.
Sprinkle minced garlic, dried thyme, dried rosemary, and add the bay leaf over the vegetables.
Place the seared chuck roast on top of the vegetables in the crockpot.
Pour diced tomatoes (undrained), beef broth, and Worcestershire sauce over the roast. Ensure the roast is mostly submerged.
If using, add the quartered potatoes around the roast.
Cover and slow cook on low for 8-10 hours or high for 4-6 hours, until fork-tender and shreddable.
Remove the roast and shred with two forks.
Optional: To thicken sauce, remove 1 cup of liquid, whisk with 2 tbsp cornstarch or flour mixed with cold liquid. Return mixture to crockpot and cook on high for 15-20 minutes.
Return shredded roast to crockpot, stir into sauce, and serve hot with preferred sides.