Preheat the oven to 350°F/175°C with an oven rack in the center. Lightly grease a 9 x 5 inch / 23 x 13 cm loaf pan with nonstick spray.

Grate the zucchini on the large holes of a box grater - you should end up with about 2 packed cups / 480 mL shredded zucchini.

In a large bowl, whisk the eggs, oil, and vanilla until well combined. Add the brown sugar and sugar and whisk well to combine. Fold in the grated zucchini, and mix until evenly incorporated.

In a medium bowl, whisk the flour, baking soda, and salt to combine. Add the flour mixture to the zucchini mixture, and stir to combine using a silicone spatula. Scrape the sides and base of the bowl well to make sure the mixture is uniformly combined. If using, fold in the nuts.

Pour the batter into the prepared pan, and spread into an even layer. Generously top the surface with turbinado sugar. (Optional: Brush a paring knife with melted butter, and draw a long line down the center of the loaf - this will help the loaf split and rise more evenly.)

Transfer the pan to the oven and bake until the edges of the loaf start to pull away from the edge of the pan, and a tester inserted into the center comes out with just a few moist crumbs attached, 60-75 minutes. (If the top of the loaf is becoming too dark before the end of bake time, cover the pan loosely with foil for the remainder of baking.)

Transfer from the oven to a cooling rack and run a small offset spatula gently around the edge of the loaf to separate it from the pan. Let the bread cool in the pan for 10 minutes before unmolding onto a wire rack to cool completely.