Grate fresh zucchini and squeeze out excess moisture using a clean kitchen towel or paper towels to prevent the muffins from becoming soggy.
In a mixing bowl, combine flour, baking powder, baking soda, salt, and cinnamon to create the dry ingredient mixture.
In another bowl, whisk together eggs, vegetable oil, vanilla extract, and a sweetener of choice such as sugar or honey until well combined.
Gradually add the dry ingredients to the wet ingredients, stirring until just combined. Fold in the grated zucchini and optional mix-ins
Divide the batter evenly among lined or greased muffin cups, filling each about two-thirds full.
Bake the zucchini muffins in a preheated oven at 350°F (175°C) for 18-20 minutes or until a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the pan for a few minutes before transferring them to a wire rack to cool completely.
Enjoy the zucchini muffins warm or at room temperature, and store any leftovers in an airtight container for up to 3 days. They can also be frozen for longer storage.