1Heat oven to 350°F. Spray 13x9-inch pan with cooking spray. In small bowl, mix topping ingredients with pastry blender or fork until crumbly; set aside.
2In large bowl, beat all cake ingredients except apples with electric mixer on medium speed 3 minutes, scraping bowl frequently. Spread batter in pan. Arrange apple slices evenly over batter. Sprinkle evenly with topping.
3Bake 55 to 60 minutes or until toothpick inserted in center comes out clean. Serve warm with ice cream or whipped cream.