Preheat oven to 350°F.
Stir together 1 1/2-cups cake mix, 2/3-cup water and eggs. Spoon into a greased 13 X 9-inch baking pan. Top with pie filling.
Cut butter into remaining cake mix. Mix until crumbly. Sprinkle over pie filling.
Bake for 25-30 minutes. Cool in pan on a wire rack.
Combine powdered sugar and 1-Tablespoon water. Drizzle over cake.