Preheat the oven to 400°.
Wash the zucchini and trim the ends off. Cut the zucchini into large chunks and place them in the bowl of a food processor. Process for 1 minute or until the zucchini is completely shredded. Set that aside.
In a large bowl, add the sugar and oil and mix well.
Add the eggs and vanilla to the oil and sugar mixture. Mix well.
Fold in the zucchini to the sugar and egg mixture.
Add the flour, baking powder, and salt to the zucchini mixture. Mix until just combined, trying not to overmix.
Spray a loaf pan with cooking spray. Add half the batter to the loaf pan. Top with ¼ cup of Nutella. Using a butter knife or a chopstick, swirl the Nutella into the batter.
Add the rest of the batter to the loaf pan and top with the other ¼ cup of Nutella. Using the same knife or chopstick, swirl the Nutella into the batter.
Bake for one hour or until a toothpick is inserted into the batter and it comes out clean. Allow the bread to cool completely before serving.