- Heat oven to 400 °F.
- Grease twelve 3-inch muffin cups or line with paper liners.
- In large bowl, combine both flours, cinnamon, baking powder, baking soda, and salt.
- In medium bowl, beat buttermilk, oat bran, brown sugar, oil, and egg until blended.
- Stir buttermilk mixture into flour mixture just until combined.
- Fold in apples.
- Divide batter among muffin cups.
- Bake 18 to 20 minutes or until wooden pick inserted in centers comes out clean.
- Cool muffins in pan 5 minutes; remove from pan and cool on wire rack.