Line a baking pan with a large sheet of heavy duty foil. On the bottom of the foil sprinkle 1 envelope of the dry onion mix, lay frozen roast on this, sprinkle another envelope on top of roast and wrap foil by folding over top and folding up the sides to make a package.
Bake in 250 degree oven for 5 or 6 hours. You will have ample gravy when done and no more attention is required. I have used this roast on many occasions. With over 40 years in the ministry, I've never once stayed home from church to cook dinner for my Sunday guests.