Place grated Zucchini, apple, squash, and spinach into a bowl (including any juices released during grating). Mix in the remaining wet ingredients.

In a separate bowl, place all the dry ingredients together and stir to combine well.

Slowly add dry ingredients into wet ingredients and mix until well incorporated. (Dry goes into wet so you have 1 fewer bowl to clean!) This will be a fairly wet batter.

Divide batter between 12 muffin cups. I use a 3-tablespoon dough scoop to make this job clean and simple. I love using these muffin liners because they make the muffin easy to remove from the tin after baking and clean up easier!

Muffins are done when the top feels firm to the touch (i.e., your finger will not leave an indent in the top of the muffin if you press gently) / when a knife comes out clean.