Preheat the oven to 350 degrees . in a bowl, sift the cake flour, baking powder, baking soda, cinnamon and nutmeg.
In another bowl, whisk the egg, sugar and oil. Stir in the zucchini, carrot and salt. Stir the flour mixture into the vegetable mixture. Mix in the bran and walnuts.
Grease a mini muffin pan with cooking spray. Fill the cups halfway with the batter. Bake for 12 to 14 minutes. Remove from the pan and let cool.