Season the beef cubes with salt and black pepper evenly.
Heat vegetable oil in a large skillet over medium-high heat. Add the beef cubes in batches and brown on all sides, about 3-4 minutes per batch. Transfer browned beef to the slow cooker.
In the same skillet, add the chopped onion and cook for 3-4 minutes until softened. Add minced garlic and cook for 1 minute more. Transfer onion and garlic to the slow cooker.
Pour beef broth into the slow cooker. Add Worcestershire sauce, dried thyme, dried rosemary, and bay leaves. Stir gently to combine.
Cover and cook on low for 6 hours, or until the beef is tender.
About 30 minutes before serving, remove bay leaves from the slow cooker.
In a small bowl, whisk together cornstarch and cold water until smooth. Stir the cornstarch mixture into the slow cooker to thicken the gravy.
Add egg noodles to the slow cooker and stir to combine. Cover and cook on high for 20-25 minutes, or until noodles are tender, stirring occasionally to prevent sticking.
Remove from heat and stir in chopped fresh parsley.
Serve hot, spooning beef and noodles with gravy onto plates.