Preparation

1. Preheat your oven to 350°F (175°C). Grease a 9 by 5 inch loaf pan and line it with parchment paper for easy removal.
2. Shred your zucchini using the medium holes on a box grater and gently squeeze it in a kitchen towel to remove excess moisture.
3. In a bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon.
4. In a separate larger bowl, whisk together the eggs, oil, brown sugar, (granulated sugar if using), and vanilla until smooth.
5. Stir the shredded zucchini into the wet mixture.
6. Add the dry ingredients to the wet ingredients and stir just until combined, do not over mix.
7. In a small bowl, combine the brown sugar and cinnamon for the swirl.

Baking

1. Pour half of the batter into the prepared loaf pan, sprinkle most of the cinnamon sugar mixture over it, then add the remaining batter. Sprinkle the rest of the cinnamon sugar on top.
2. Use a butter knife to carefully create a few gentle swirls without over mixing.
3. Bake for 50 to 65 minutes, starting to check for doneness at 50 minutes. A toothpick should come out with moist crumbs, not wet batter.

Serving

1. Once cooled, slice the bread thickly and enjoy. Avoid tasting it standing at the counter as it is quite tempting!