Make two pans of your favorite cornbread. This can be done a day in advance. Crumble the cornbread in to a large mixing bowl. You should have 5 cups of crumbled cornbread.
Pre-heat the oven to 350.
Saute the diced onion and mushrooms in a small amount of vegetable oil. Stirring occasionally cook until golden brown.
Mix the browned onions and mushrooms with the crumbled cornbread. Add in two cups of vegetable broth.
Add to a 9x13 casserole baking dish and bake at 350 for 30 minutes.