Preheat the oven to 350 degrees Fahrenheit and grease a square 8 x 8 baking pan with vegan butter and line with parchment paper.
Begin by adding the flaxseed meal + water to a small bowl, stirring until combined and letting it sit for 5-10 minutes. Set aside.
In a large bowl, add the oil and sugar together, whisking until combined.
Add in the flaxseed meal mixture, milk, and vanilla, whisking to combine. Add in the grated zucchini and stir to combine using a wooden spoon.
Now, add in flour, cocoa powder, cinnamon, salt, and baking powder, mixing everything together until combined and smooth. NOTE: Batter will be thick, that's OK.
Finally, add in the chopped chocolate and fold them in gently.
Pour the batter into the prepared baking pan and evenly spread it in. Top with rainbow sprinkles.
Bake for 35-40 minutes or until the center comes out "mostly clean".
Remove from oven and let cool for about 20 minutes or so before lifting brownies out from the pan.
Once fully removed, let the brownies cool for another 10-15 minutes before slicing into squares.
Serve each brownie with your favorite non-dairy ice cream, fruit, or dairy-free milk, if desired.
Bon Appetit!