Preheat the oven to 350 degrees . Line two standard 12-cup muffin pans with 20 baking liners. using a stand mixer fitted with the whisk attachment, beat the butter and sugar on high speed until fluffy, about 2 minutes. reduce speed to medium and beat in the eggs one at a time, and then the vanilla.
In a medium bowl, whisk both flours, flaxseed, cinnamon, baking soda, salt and nutmeg until well combined. with the mixer running on low speed, gradually add the flour mixture to the butter mixture. Beat until just combined (do not overmix). fold in the zucchini and raisins, if using.
Spoon the batter into the baking liners, filling each about three-quarters full. Bake until golden and a toothpick inserted into the center comes out clean, 25 to 30 minutes. Let cool in the pans on a wire rack.