Preheat your oven to 350°F (175°C) and grease a 9x5 inch loaf pan.

In a medium bowl, whisk together the all-purpose flour, baking soda, baking powder, salt, and ground cinnamon.

In a large mixing bowl, combine the vegetable oil, granulated sugar, and brown sugar. Beat until smooth, then add eggs one at a time followed by vanilla extract.

Fold in the grated zucchini, then gradually add the dry mixture, stirring gently until just combined. Fold in nuts if using.

Mix 1 tablespoon of cinnamon with sugar for the cinnamon sugar swirl.

Pour half of the batter into the loaf pan, sprinkle with half of the cinnamon sugar, pour in remaining batter and top with rest of the cinnamon sugar. Swirl with a knife.

Bake for 55 to 65 minutes or until a toothpick inserted in the center comes out clean.

Cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.