In large bowl, combine flours, oats, brown sugar, baking powder, baking soda, cinnamon and salt. Stir in buttermilk, applesauce, oil and egg; mix well. Fold in raisins. Cover tightly and refrigerate overnight. (If desired, muffins can be baked immediately.) Preheat oven to 400 degrees. Grease or paper-line 12 (2 1/2-inch) muffin cups. Prepare batter as directed. Spoon batter into cups. Bake 18 to 20 minutes or until wooden pick in chenter comes out clean. Remove from pan.