Combine kosher salt, brown sugar, and black pepper in a small bowl. Rub this spice mixture evenly over all sides of the beef chuck roast pieces to season them thoroughly.

Heat olive oil in a large pot or skillet over medium-high heat. Sear each piece of the seasoned beef chuck roast on all sides until a dark brown crust forms. Work in batches if needed to avoid crowding the pan. Transfer the seared meat to the slow cooker. I find that searing the beef really deepens the final flavor, so don't skip this step if you have time!

Lower the heat to medium and add the coarsely chopped onion to the pot with the remaining oil and beef drippings. Sauté for 2-3 minutes, scraping up any browned bits stuck to the bottom. Once softened and fragrant, add the onions to the slow cooker on top of the beef.

Add minced garlic, Italian seasoning, smoked paprika, Worcestershire sauce, and soy sauce to the slow cooker with the beef and onions. In a separate bowl, whisk together beef broth (or stock) and cornstarch until smooth. Pour this liquid over the assembled ingredients in the slow cooker. The top of the roast may not be completely covered by the liquid, which is fine.

Cover the slow cooker and cook the mixture on LOW for 6-7 hours or on HIGH for 3.5-4 hours, until the beef begins to get tender. If I have the time, I always cook on LOW for the best, most succulent results.

Add the halved baby potatoes and carrot pieces to the slow cooker. Use the back of a spoon to gently push them into the broth so they're mostly submerged. Cover and continue cooking for 3 more hours on LOW or 1.5 hours on HIGH, until the vegetables are tender.

Remove the cooked beef from the slow cooker and shred it into large pieces. Arrange the beef on a serving platter and spoon over some of the flavorful pan juices. Use a slotted spoon to remove the potatoes and carrots, and serve them alongside the beef.