Place beef roast in slow cooker. Sprinkle onion soup mix on top. Add mushroom soup and garlic and smear on top of roast. Add beef broth.
Put lid on crockpot and cook 9 to 10 hours on LOW.
Remove lid and shred beef using 2 forks. Add noodles and enough water to mostly submerge the noodles. I try to use as little water as possible because I don't want to water down the flavor. It's ok if some of the noodles are sticking slightly out of the liquid. There is enough moisture and condensation in the crock pot to cook them thoroughly.
Cook for 1 hour. Check for seasoning and add salt and pepper to taste.