Begin by patting the beef chuck roast dry using paper towels. Cut the beef into large chunks, then season with salt, pepper, and a light dusting of all-purpose flour.

In a skillet, heat vegetable oil over medium-high heat. Add beef chunks to the skillet and brown on all sides for about 2-3 minutes per side.

In the same skillet, add chopped yellow onion and sauté for about 5 minutes until golden. Stir in minced garlic and cook for an additional minute, then pour in beef broth.

Pour the onion and broth mixture over the browned beef in the slow cooker. Add sliced mushrooms and sprinkle dried thyme. Stir gently and cover.

After 4 hours, remove the lid and stir in the wide egg noodles, ensuring they are submerged in broth. Cover again and cook on LOW for an additional 30 minutes.

Once the noodles are tender, turn off the slow cooker and let the dish rest for 5-10 minutes before serving. Garnish with dried parsley.