Empty 2 cans of cream of mushroom soup into crockpot. Pour in 1 soup can of milk. Whisk together. Place roast into crockpot and spoon soup mixture over roast. Let cook for 8 to 10 hours on low.
After 8 to 10 hours, pull roast out of crockpot. Cut into serving size pieces. Set aside.
Whisk the gravy mixture. Add 1 envelope of Knorr Hunter Sauce. Add salt and pepper to taste. If too thin, add a small amount of corn starch/water. Put roast pieces back into crockpot. Add mushrooms if you would like. Cook for another 2 hours.
I serve this with lots of mashed potatoes. It makes lots of gravy. For leftovers, I add carrots, potatoes, onion, and any leftover vegetables I might have to make a stew.