Shred unpeeled zucchini by hand with a box grater, or use a food processor. Set aside.
Using a mixer, blend sugar with oil until incorporated. Add egg and beat 1 minute until creamy. Add vanilla and stir.
In a separate bowl, combine flour, baking powder, baking soda, salt and cinnamon. Whisk together.
Alternate adding dry ingredients to wet ingredients, alternating with buttermilk. Blend well with mixer while adding ingredients.
Fold in shredded zucchini, chocolate chunks and pecans. Stir batter and scoop into muffin liners in a tin pan. Fill to the very top. Add a few extra chocolate chips to the top of each muffin if desired.
Bake at 425 for 5 minutes, then reduce heat to 375 for 15 minutes until tops rise and spring back to the touch. Take care not to over bake or muffins will be dry.
Notes
All ovens are different as well as altitudes. Be sure to check your temperature and adjust accordingly. You may need to bake muffins longer if necessary.
If the zucchini is dripping wet with water, dab it with a paper towel. Otherwise, you do not need to drain it because the moisture is needed in the recipe to keep from adding extra oil.
Be sure to fill the muffin tin cups to the very top. Muffin tops will rise quickly when initially baked in a high temperature oven.