In a small bowl, sift together the flour, baking powder, baking soda, salt, cinnamon, and ginger. Using a rubber spatula, fold the mixture into the egg-sugar mixture. When most of the flour mixture has been incorporated, add the carrots, raisins, and walnuts and continue to fold until the batter is combined. Divide evenly among the prepared muffin cups (or pour the batter into the prepared cake pan).