Preheat the oven to 375°F. Grease a 9x13-inch baking dish with olive oil or cooking spray.
In a large bowl, combine the grated zucchini and salt. Let it sit for about 10 minutes to draw out excess moisture. After 10 minutes, squeeze the zucchini in a clean kitchen towel to remove as much liquid as possible.
In another bowl, whisk together the flour, baking powder, black pepper, garlic powder, and dried oregano.
In a separate bowl, beat the eggs, then add the Parmesan cheese, milk, and olive oil. Mix until well combined.
Gradually add the dry ingredients to the egg mixture, stirring until just combined. Fold in the squeezed zucchini and chopped basil, if using.
Pour the mixture 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.
Let it cool for about 10 minutes before slicing into squares. Serve warm or at room temperature.