In a large skillet, heat olive oil over medium-high heat.
Add the beef cubes in batches and brown on all sides, about 4-5 minutes per batch. Transfer browned beef to the crock pot.
Add diced onion and minced garlic to the skillet and sauté for 2-3 minutes until softened. Transfer to the crock pot.
In a small bowl, whisk together beef broth, Worcestershire sauce, dried thyme, dried rosemary, salt, and black pepper.
Pour the broth mixture over the beef and onions in the crock pot.
Cover and cook on low for 7 hours, or until the beef is tender.
About 20 minutes before serving, bring a large pot of salted water to a boil.
Cook egg noodles according to package instructions until al dente, about 8-10 minutes. Drain and toss with unsalted butter.
Once the beef is cooked, remove 1 cup of the cooking liquid from the crock pot and place it in a small bowl.
Whisk the all-purpose flour into the reserved cooking liquid until smooth.
Pour the flour mixture back into the crock pot and stir well to thicken the sauce.
Cook uncovered on high for an additional 10-15 minutes until sauce thickens.
Serve the beef and sauce over the buttered egg noodles and garnish with chopped fresh parsley.