Preheat oven to directions on box. Mix cake mix to directions on box, using 1/2 cup water and 1 egg. Grease a 9 by 9-inch square cake pan or disposable cake pan with butter. Pour in cake batter. Toss apples with cinnamon and sugar and sprinkle on top of cake batter. Bake 20 to 25 minutes. Serve warm cake squares with small scoops of butter pecan or rum raisin ice cream.