Heat oven to 375°F. Heat pie filling in large saucepan over medium heat until very hot, stirring occasionally.
Meanwhile, in large bowl, combine cake mix and butter; blend at low speed for 45 to 60 seconds or until crumbly. Place 1 1/2 cups cake mixture in medium bowl; stir in walnuts and cinnamon until well mixed. Add milk to cake mixture in large bowl; stir until dry particles are moistened.
Spoon hot pie filling into ungreased 13x9-inch pan.* Top with heaping spoonfuls of cake batter. Sprinkle with walnut mixture.
Bake at 375°F. for 30 to 40 minutes or until topping is golden brown and cracks appear dry. Cool 30 minutes. Serve warm with ice cream.