Supreme Rice Casserole
["1 stick butter, cut in chunks", "1 1/3 c. uncooked instant rice", "1 (10 3/4 oz.) can onion soup", "1/2 tsp. pepper", "1/3 lb. fresh mushrooms, sliced or 1 (4 oz.) can mushrooms"]
["Combine all ingredients in baking dish.", "Cover tightly and microwave 5 minutes on High.", "Stir and microwave 5 additional minutes on 50% power.", "Let stand several minutes before serving."]
["butter", "rice", "onion soup", "pepper", "fresh mushrooms"]