Preheat oven to 375’F
Grease an 8×8 baking dish (you can use smaller or larger but cooking times will vary. For a smaller pan, you will have to bake longer to ensure it’s fully cooked in the center).
Shred a small zucchini into a cheese cloth (a bunch of paper towels will work as well) and squeeze out excess moisture, then set aside
Combine oats, raisins, walnuts, baking powder, cinnamon, chia seeds and salt in a medium mixing bowl
Combine brown sugar, milk, egg and vanilla in a separate mixing bowl
Add wet to dry mixture, folding gently to combine. Let sit for 2 minutes to allow chia seeds to soak up some of the moisture
Gently fold in shredded zucchini and chocolate chips
Pour into greased baking dish using a spatula to spread the mixture evenly throughout the dish
Bake for 30 minutes until golden brown (because every oven is different, I recommend plunging a knife or cake tester into the center of the dish to test if it’s done, if it comes out clean or just a bit wet, it’s done).
Allow to cool completely before slicing. You don’t HAVE to wait, but note that the squares may fall apart a bit if you’re scooping it out of the dish right when it comes from the oven.