Trim off the ends of the zucchini, then grate. Squeeze out the excess water: place a kitchen towel on the counter, top it with a few paper towels, then place the grated zucchini in the center. Wrap the towels up and around the zucchini, then thoroughly squeeze it over the sink (or over a bowl) to remove as much moisture as possible. Repeat a second time, replacing the paper towels.
In a large mixing bowl, place the squeezed zucchini, oil, yogurt, maple syrup, brown sugar, eggs, and vanilla. Whisk until combined.
In a separate medium bowl, whisk together the flour, baking powder, cinnamon, and salt.
Pour the dry ingredients into the bowl with wet ingredients, with a wooden spoon or rubber spatula, stir by hand just until they are blended. Do not over mix.
Allow the batter to rest at room temperature for 30 minutes (this allows the dry and wet ingredients to better incorporate, will result in muffins with a higher rise in the oven and allows the gluten in the flour to relax so you have a more tender muffin). Meanwhile, place a rack in the center of your oven and preheat to 425°F . Line a 12-cup muffin tin with paper liners or lightly coat with nonstick spray.
Once the batter has rested, give it one big, gentle stir, then scoop into the prepared muffin cups, dividing evenly between each (the cups will be about three-fourths or so of the way full).
Bake the zucchini muffins for 5 minutes at 425°F, then without opening the oven, reduce the temperature to 350°F and continue baking for an additional 15 to 18 minutes, until the tops of the muffins are risen and domed and a toothpick inserted in the center of a muffin comes out clean.
Let the muffins cool in the pan for 5 minutes in the pan, then gently transfer to a wire rack to cool completely…or enjoy them warm immediately (who could blame you?!).
Notes
TO STORE: Store muffins in a paper towel-lined airtight storage container at room temperature for up to 4 days.
TO FREEZE: Individually wrap each muffin in plastic, place in a ziptop bag, and freeze for up to 2 months.