Spinach-Cheese Squares
["1/2 stick butter", "3 eggs", "1 c. flour", "1 c. milk", "1 tsp. salt", "1 tsp. baking powder", "1 lb. Cheddar cheese, grated", "1 (1 oz.) pkg. frozen spinach, drained", "1 small onion, minced", "6 medium mushrooms, chopped"]
["Melt butter in 9 x 13-inch pan.", "Set aside.", "Mix all remaining ingredients in a bowl.", "Pour over butter.", "Bake for 35 minutes at 350\u00b0.", "Let cool before cutting."]
["butter", "eggs", "flour", "milk", "salt", "baking powder", "Cheddar cheese", "frozen spinach", "onion", "mushrooms"]