Pat the chuck roast dry and season generously with salt and pepper. Heat olive oil in a large skillet over medium-high heat. Sear the roast on all sides until a deep brown crust forms. Transfer the seared beef to the slow cooker.

In the same skillet, add the sliced onion and cook until softened, about 3-4 minutes. Add the minced garlic and cook for 1 minute more until fragrant.

Pour the beef broth into the skillet to deglaze, scraping up any browned bits. Stir in the soy sauce, Worcestershire sauce, thyme, and rosemary. Pour the entire mixture over the beef in the slow cooker.

Cover and cook on low for 8-10 hours or on high for 4-5 hours, until the beef is fall-apart tender.

Remove the beef and shred it using two forks, then return it to the slow cooker. In a small bowl, whisk together the cornstarch and cold water to make a slurry. Stir the slurry into the slow cooker. Cover and cook on high for 15-20 minutes until the sauce has thickened.

While the sauce thickens, cook the egg noodles according to package directions. Serve the beef and gravy over the cooked noodles, garnished with fresh parsley.