1. Heat oven to 350ºF. Combine oats, nuts, sugar, butter and 1/2 tsp. cinnamon; mix well.
2. Beat cake mix, eggs, water, oil and remaining cinnamon in large bowl with mixer until blended. Add dry pudding mix; beat 2 min. Stir in apples.
3. Pour into 13x9-inch pan sprayed with cooking spray; sprinkle with oat mixture.
4. Bake 45 min. or until toothpick inserted in centre comes out clean. Cool.
Special Extra: Serve topped with thawed Cool Whip Whipped Topping.
Substitute: Prepare using quick-cooking oats.