Preheat oven to 350 degrees.
Grate zucchini and pat dry using paper towels.
Add the grated zucchini to a large bowl with the light brown sugar, olive oil, greek yogurt, vanilla extract, and eggs.
Combine the wet ingredients with a whisk.
In a small bowl, combine the flour, baking powder, baking soda, lemon zest, cinnamon, and nutmeg using a rubber spatula.
Pour the dry ingredients into the wet ingredients and fold together.
Next, add the cranberries and mix to combine. If you're including walnuts, add the walnuts to the large bowl and mix to combine.
Butter an 8-inch loaf pan.
Pour the batter into the loaf ban and spread out evenly using your rubber spatula.
Sprinkle extra grated zucchini on top of the batter. Then, top with extra cranberries and lightly push them into the top of the batter.
Bake for 45-55 minutes. When a toothpick is inserted into the middle of the loaf and comes out clean, the bread is done.
Cool for ten minutes before removing the bread and transferring to a wire rack and cooling completely.