PREHEAT oven to 350°F. Lightly coat 8-inch square baking pan with cooking spray and set aside.
LIGHTLY coat baking sheet with cooking spray; sprinkle with flaxseeds and walnuts; bake until lightly toasted, about 7 minutes. Set aside. Keep oven on.
IN large bowl, combine oats, oat and bran cereals, brown sugar, cinnamon and salt. Mix well.
POUR buttermilk into large glass measuring cup. With fork, stir in egg, oil and orange peel until well blended.
ADD buttermilk mixture to oat mixture and stir with rubber spatula just until moistened. Fold in dried apricots, then toasted flaxseeds and walnuts. Transfer to prepared baking pan, spreading evenly. Sprinkle top with sugar.
BAKE until a toothpick inserted in center comes out clean, 30 to 35 minutes. Transfer to wire rack to cool completely, then cut into 12 bars.
