This is the recipe that I use on Wednesdays for my church crowd. It feeds about 30 people per pan. I use 2" deep buffet pans. I have had a lot of people ask how to make this much at one time. It's a good recipe when you are preparing for a reunion or church social. If you want to make a 13X9 pan, split the recipe in half.
2 sticks Butter
1 Onion, sliced
6 cups Rice
4 cans sliced Mushrooms, with liquid
4 cans Beef Broth
4 cans Beef Consommé
Preheat oven to 350 degrees. Sauté onions in butter and put in shallow buffet pan. Stir in rice, and liquids. Add mushrooms and liquid. Cover and bake for 1 hour or until liquid is absorbed and rice is tender.