Step 1) Preheat oven to 325°F. Spray a 13 x 9-inch pan with cooking spray.
Step 2) Combine whole wheat flour, all-purpose flour, oats, baking powder and salt in medium bowl; set aside.
Step 3) Beat together oil and brown sugar in large bowl of electric mixer until smooth. Beat in eggs, one at a time; blend in vanilla. Stir in flour mixture, chocolate chips and nuts.
Step 4) Spread batter in prepared pan. Bake 35 to 40 minutes, or until toothpick inserted in center comes out clean. Cool completely on wire rack; cut into bars.