Recipe(tried): Mushroom Sauce (like Ponderosa Steakhouse)

I work for ponderosa steakhouse. the mushroom sauce that you speak of, is it the one for the salisbury steak? if so, then it is 2 quarts (or 8 cups) of brown beef gravy, 2 quarts(or 8 cups) thinly sliced and separated white onions and 4 cups of sliced mushrooms. 1 tsp salt and 1 tsp pepper, and 8 ouces of butter. this recipe makes ALOT. so, place the onions and mushrooms in a pot, add butter salt and pepper. cook on high stirring. when the onions are transparent, add the brown beef gravy prepared, and mix together with a spoon. lower heat, and bring to a simmer. then, spoon over the salisbury steak and serve. this has a refridgerator life of 3 days. and, like i said, it MAKES ALOT!!!!!