In a slow cooker, combine the beef chuck roast, beef broth, soy sauce, hoisin sauce, sesame oil, garlic, and ginger. Stir well to combine.
Add the sliced mushrooms to the slow cooker. Cover and cook on low for 6-8 hours or on high for 3-4 hours until the beef is tender.
About 30 minutes before serving, add the baby spinach and green onions to the slow cooker.
In the last 10 minutes of cooking, add the ramen noodles to the slow cooker. Stir to combine and let them cook until tender.
Season with salt and pepper to taste before serving.