Spinach Squares
["4 Tbsp. butter or margarine", "3 eggs", "1 c. flour", "1 c. milk", "1/2 tsp. salt", "1 tsp. baking powder", "1 lb. Cheddar cheese, grated", "1 (10 oz.) pkg. frozen chopped spinach or broccoli, thawed and drained", "1 small onion, chopped", "1/2 c. mushrooms, chopped (optional)"]
["Preheat oven to 350\u00b0.", "Melt butter in a 13 x 9-inch pan.", "Mix remaining ingredients together in large mixing bowl.", "Spoon into pan.", "Bake for 35 minutes.", "Cool slightly before cutting into squares.", "Serve warm or at room temperature."]
["butter", "eggs", "flour", "milk", "salt", "baking powder", "Cheddar cheese", "broccoli", "onion", "mushrooms"]