Preheat oven to 425 degrees and grease or line a 12-cup muffin tin.
In a large bowl, whisk together flour, baking powder, baking soda, salt and cinnamon. Add in oil, sugar, brown sugar, eggs and vanilla and mix until just combined. Fold in zucchini and chocolate chips.
If desired, make streusel by combining flour, sugar and a pinch of salt, Using your fingers or two forks, cut in the butter until the mixture resembles coarse crumbs.
Divide batter equally among muffin cups. Top with streusel, or additional chocolate chips if desired. Bake at 425 degrees for five minutes. Lower heat to 375 degrees and bake an additional 12-15 minutes. Allow to cool for about five minutes before removing from muffin tin. Enjoy!