Preheat oven to 350°F. Mix the cream of mushroom soup and the onion soup packet together in a small bowl.

Cut slits into the roast on all sides that are deep enough to pack with pepperoni. Use fingers or other utensil to pack each slit with pepperoni. Season all sides.

Line the bottom of a large roasting pan with tin foil. Place a dollop of the soup mixture in the center of the foil and spread outward until it's about the size of the roast. Place roast in the center of the foil and cover all sides with the remaining soup mixture. Cover with another piece of tin foil and smooth the foil down over the sides. Bring the bottom foil up the sides and over the top. Cover pan with lid and bake for two hours.

While the roast is baking, cut the vegetables into whatever sized pieces your family enjoys. Mix all the vegetables (except for the mushrooms - they go in later) in a large bowl and season if desired. When the two hours is finished, place the vegetables (except for the mushrooms) around the roast. Replace lid and bake for one hour.

After the hour is up, remove tin foil. Place mushrooms on top and bake for a half an hour.

Arm roast tends to fall apart at this point, which is why we love it. If you want slices, you can substitute a different cut of meat.