Preheat the oven to 350°F
Prepare a muffin tray by lining it with either paper or silicone liners
Peel your zucchini (this is key if you have little ones who are reluctant to eat anything green!)
Finely grate 2 cups of zucchini, using either a box grater or food processor with a grating attachment
Squeeze out as much excess water as possible, either by hand or by placing the grated zucchini in a mesh strainer and pressing with a wooden spoon
To the bowl of a stand mixer, add sourdough starter, eggs, melted butter, sugar, and vanilla. With the paddle attachment, mix until well combined
In a separate medium bowl, combine flour, baking soda, baking powder, salt, and cinnamon until evenly mixed
Next, gradually add the flour mixture to the wet ingredients in the stand mixer bowl, mixing on low speed until just combined. Be careful not to overmix to keep the muffins light and fluffy!
After combining wet and dry ingredients, gently fold in the grated zucchini until evenly distributed throughout the batter.
Spoon the batter into the prepared muffin tray, filling each cup about two thirds full
Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean and the tops are golden brown
Once baked, remove the muffins from the oven and allow them to cool in the tray for 5 minutes before transferring them to a wire rack to cool completely at room temperature
Serve and enjoy!