Combine whole wheat flour, white flour, baking soda, salt, cinnamon, and allspice in a large bowl.

Add brown sugar, all-bran cereal, and natural bran to the dry ingredients.

In a separate bowl, beat eggs and egg whites.

Add buttermilk, applesauce, and molasses to the egg mixture, mixing well.

Combine the wet and dry ingredients, stirring until just combined.

Fold in raisins and grated carrots.

Stir well to ensure all ingredients are evenly distributed.

Refrigerate the batter for at least 6 hours or overnight to allow the cereal to soak up the liquid.

Before baking, stir the batter well.

Preheat oven to 400°F (200°C).

Fill muffin tins 1/2 full with batter.

Bake for 17-20 minutes, or until a toothpick inserted into the center comes out clean.

Cool in the muffin tins for a few minutes before transferring to a wire rack to cool completely.