Heat oven to 350°F. Spray 9-inch square pan with cooking spray. In medium bowl, mix 1 cup whole wheat flour, the all-purpose flour, baking powder, baking soda and salt. In large bowl, beat egg, brown sugar, oil, orange juice concentrate and vanilla with electric mixer on medium speed until smooth. Stir in flour mixture until blended. Reserve 1/2 cup dough mixture for topping.