Season the beef with salt and black pepper.
Heat olive oil in a skillet over medium-high heat. Brown the beef in batches, then transfer it to the slow cooker.
In the same skillet, sauté onion, carrots, and celery until softened, about 5 minutes. Add garlic and cook for 1 more minute.
Transfer vegetables to the slow cooker. Add beef broth, thyme, and rosemary.
Cover and cook on low for 6–8 hours or high for 3–4 hours, until the beef is tender.
Stir in the egg noodles, cover, and cook on high for about 30 minutes until noodles are tender. This step completes the Slow Cooker Beef and Noodles perfectly.
Stir in parsley and serve warm.