Step 1

Heat oven to 350°F. Spray bottom only of 13x9-inch pan with cooking spray.

Step 2

In large bowl, beat sugars, buttermilk, oil, vanilla and eggs with electric mixer on low speed 20 to 30 seconds or until blended. Add all remaining ingredients except apples and walnuts; beat on low speed about 1 minute or until blended. Stir in apples and walnuts. Spread batter in pan.

Step 3

Bake 40 to 45 minutes or until toothpick inserted in center comes out clean. Cool in pan on cooling rack 1 hour.