If desired, warm canola oil over medium-high heat in a large skillet and brown the chuck roast on each side for 1 to 2 minutes to enhance flavor.
Transfer the roast into the crock pot and pour in beef broth, sprinkle chopped onion, add minced garlic, Worcestershire sauce, and Italian seasoning evenly over the meat.
Cover the crock pot and let it cook on Low for 6 to 7 hours or on High for around 4 hours until the beef becomes very tender.
Shred the cooked beef directly in the crock pot using two forks and season with salt and pepper to your liking.
Mix in the wide egg noodles and optional mushrooms with the shredded beef and broth.
Set the crock pot to High, cover it again, and cook for 10 to 20 minutes until the noodles reach the ideal tenderness, keeping an eye on them as cooking times may vary.
Stir in either the heavy cream or the cornstarch slurry and allow the sauce to bubble on High for a few minutes until it thickens to a gravy consistency.
Serve the hearty beef and noodles hot in deep bowls, optionally garnished with fresh parsley for color and flavor.