Preheat oven to 375 degrees F. Line a standard muffin tin with paper liners or grease with cooking spray.

Add raisins to a small bowl and soak them in hot water for 10 minutes, to allow them to plump. Meanwhile mix together bran and buttermilk, let stand 5 minutes.

Grate the carrots and chop walnuts (if using) and set aside.

Add egg, egg white, oil, sugar and vanilla to a mixing bowl and mix by hand until combined. Stir in bran mixture. Stir in carrots, nuts, raisins.

Stir together flour, salt, soda, and baking powder, then add to the batter, stirring just until combined (don’t over mix!).

Divide batter among muffin tins, filling them full. Bake for 16-18 minutes or until a toothpick inserted in the center comes out clean.

Allow to cool for a few minutes in the pan before removing to a wire cooling rack to cool completely.