Preheat your oven to 350 and get your muffin tins ready (spray with cooking spray or line with muffin liners). Take your clean zucchini and grate it.
In a small bowl, combine the dry ingredients (flour, baking powder, baking soda, salt and cinnamon); set aside.
In a mixing bowl, beat oil, apple sauce and eggs. Once combined, add in vanilla, lemon zest and brown sugar; beat well. Add in flour mixture and just mix for a moment - you should still see flour streaks). Now add the zucchini and mix gently (I like to do this last mixing by hand because over-mixing at this point is what causes muffins and quick breads to become tough).
Spoon the batter into muffin tins (you can put all of this batter in regular muffin tins which will make very large muffins or split the batter into 24 regular muffins or 36 mini muffin tins). Bake the mini muffins for about 10-15 minutes and the regular ones for about 20 minutes (over stuffed regular muffins will take closer to 25-35 minutes - they should spring back when touched in the middle).
Remove the muffins from the tins and cool on a rack.
You can eat them like this (maybe dusted with icing sugar!) or ice them with cream cheese icing).
If you're icing them, either pipe it onto the top or push the piping bag into the middle of the muffin and squeeze to release some of the icing into the middle of the muffin...as you push the icing into the middle, lift out the bag and keep squeezing to pipe a dollop onto the top.
You can serve them or freeze them - even iced, they will freeze well!