Preheat the oven to 350 degrees F. Line a 12-cup muffin tin with paper liners. In a large bowl, combine the flour, baking powder, baking soda, salt and cinnamon. Whisk well. Using an electric mixer, cream the butter and sugar together until light and fluffy. Scrape the bowl and add the egg. Beat in.
With the mixer on low, slowly add the dry mixture to the wet mixture until just combined. Stir in the zucchini and lemon zest.
Use a 1/4-cup scoop to evenly distribute the batter between the muffin liners. They should be 2/3 full. Dollop 1 teaspoon of Nutella on top of each scoop of batter and swirl with a toothpick.
Bake for approximately 15-20 minutes. Check the centers with a toothpick. The toothpick should come out clean before removing the muffins from the oven.
NOTE: This recipe can also be made in two loaf pans. Bake for 35-50 minutes.