Try to find two 4 lb. chuck roasts, and cut the excess slab of fat off the top. Cut into LARGE bite-sized pieces because beef shrinks when it cooks. You want to end up with nice big chunks! :).
In large metal roaster that you can use on the stove, lightly brown meat on all sides over medium-high heat in a little oil. You may have to do this in frying pan(s).
*Pepper beef lightly to liberally with coarse ground pepper as you add it to the roaster or frying pan. (Should take about 10 minutes.).
When beef is lightly browned on the outside, add broth, onion, soup mix, A-1, garlic, butter and a nice amount of salt. Add salt a 1/2 teaspoons at a time so you don't over do it.
Bring to a boil, cover with lid, turn down heat and simmer for 1 1/2 hours.
Add mushrooms, recover, and simmer 15-20 minutes longer.
Mix cornstarch and cold water, add, stirring. Simmer, stirring only occasionally, for another 5 minutes til thickened a bit.
Fold in cooked, drained noodles.
Serve with warm crusty bread and butter, and a side vegetable such as green beans, or salad.
*You can add another 1/2 to 1 bag more cooked noodles if you want to stretch this out. I make it hearty, full of lots of meat, though; when it's being considered as a "main dish".
If you stretch it out though, you may need to add a cup or so of beef bouillon. Just see what you end up with, add as needed.
**! This last time I made this, I added 1 tbsp horseradish and 1 tbsp spicy brown mustard to the pot while the beef was simmering. It was EVEN BETTER! *Don't worry, it doesn't taste like you added it, it just added more flavor and totally mellowed out especially after the noodles were added and sat on LOW HEAT for about another hour or so.I took this to my sister's Christmas party and everyone loved it! People even asked for the recipe. :) (I should have thought of it before, because that's how I make my pot roast anyways! :) And NO ONE knows it's in there!) *I used (about)6 1/2 lbs. beef, 2 1/2 bags noodles and added an extra 3 tbsp butter because I thought I had added a bit too much salt. It was really good! Hope ya try it! :).