Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking dish or line it with parchment paper.

In a large bowl, combine the grated zucchini and salt. Let it sit for about 10 minutes to draw out moisture, then squeeze out excess liquid using a clean kitchen towel.

In another bowl, whisk together the flour, baking powder, baking soda, black pepper, garlic powder, and onion powder.

In a separate bowl, beat the eggs, then add the milk and olive oil, mixing until well combined.

Stir the wet ingredients into the dry ingredients until just combined. Fold in the squeezed zucchini, cheddar cheese, Parmesan cheese, and parsley if using.

Pour the batter into the prepared baking dish and spread it evenly.

Bake for 25-30 minutes or until the top is golden brown and a toothpick inserted in the center comes out clean.

Allow to cool for a few minutes before slicing into squares and serving.