Preheat oven to 350 degrees F. Butter a ceramic baking dish.

Bring 4 quarts of water to boil in a large saucepan. Add Reames Homestyle Flat Dumplings allow water to return to a boil, lower heat and simmer for 20 minutes. Drain.In sauté pan, heat oil and cook onions for 2 to 3 minutes or until tender. Add mushrooms and continue to cook until mushrooms are golden. Remove from heat. In a large mixing bowl, combine all ingredients and toss gently to cover all with sauce. Spoon into prepared dish and bake 30 to 35 minutes or until casserole is heated thoroughly. Serve.