12-ounce can regular cola
10-3/4 ounce can cream of mushroom soup
3 to 4-pound boneless chuck roast
2 onions, thinly sliced
Combine cola and soup together and set aside. Place chuck roast in baking pan and pour soup mixture on top. Add onions.
Cover and bake at 325 degrees for 2-1/2 hours or until roast is cooked to your liking.