Adjust an oven rack to the middle position and preheat the oven to 350 degrees (original instructions were for 375 degrees). Generously coat a 9X5-inch loaf pan with cooking spray or cooking spray with flour.
Chop the ends off the zucchini (just 1/4-inch off each end) and finely shred the zucchini, peel and all. Place the shredded zucchini in a clean kitchen towel (or nut milk bag), wrap the towel, and wring the ends (like a an old-fashioned candy wrapper) to squeeze out all the excess water. You should have about 1 1/2 cups of dry zucchini. Set the zucchini aside.
In a large bowl, whisk together the flour, baking soda, baking powder, cinnamon, allspice, and salt. In a smaller bowl, whisk the sugar, yogurt, eggs, lemon juice or sour cream, and butter until combined.
Gently fold the yogurt mixture and zucchini into the dry ingredients, using a rubber spatula to fold the ingredients together until just combined - don't overmix! Transfer the batter to the prepared pan.
Bake until golden brown and a thin knife or skewer inserted in the center comes out clean or with a few moist crumbs attached, 45-60 minutes. Cool for 10 minutes then turn out into wire rack to cool for at least 1 hour. Store well-covered for up to three days.
Notes
Loaf Pans: the batter can be baked in a three to four mini loaf pans or as muffins (yield will be about 12-16)Whole Wheat Flour: this recipe works well subbing in half whole wheat flour for half of the all-purpose flour. I recommend using the following varieties for the best results: hard white wheat, soft white wheat, kamut, einkhorn. Lemon Juice/Sour Cream: you can easily omit the lemon juice and increase the yogurt or sour cream to 1/3 cup. Sugar: you can decrease the sugar to 1 cup for a less sweet version (however, I recommend making it per the recipe the first time so you know exactly how much you'd like to decrease the sugar, if any).