Cheesy Zucchini Casserole

Prep the oven: Preheat the oven to 375°F and lightly grease a 3-quart baking dish.
Salt the zucchini: Place the grated zucchini in a colander, sprinkle with the salt, and let it sit for 10 minutes. Squeeze out as much liquid as possible using a clean kitchen towel.
5 cups grated zucchini, 1 teaspoon kosher salt
Mix the filling: In a large bowl, combine the zucchini, black pepper, Italian seasoning, onion powder, garlic, eggs, ½ cup Parmesan, mozzarella, and cheddar until evenly mixed.
5 cups grated zucchini, ¼ teaspoon black pepper, 1 teaspoon Italian seasoning, ½ teaspoon onion powder, 1 tablespoon minced garlic, 2 large eggs, ½ cup grated Parmesan cheese, ½ cup shredded cheddar, 1 cup shredded mozzarella
Fill the baking dish: Spread the mixture into the prepared baking dish and smooth the top into an even layer.
Bake: Bake uncovered for 20 minutes, or until the edges are bubbling and the center is mostly set.
Make the topping: Mix together the Panko breadcrumbs, melted butter, and the remaining 2 tablespoons Parmesan.
½ cup Panko breadcrumbs, 1 tablespoon salted butter, ½ cup grated Parmesan cheese
Finish baking: Sprinkle the topping evenly over the casserole and bake for another 5–10 minutes, until golden brown and crisp.
Serve: Let the casserole rest for 5 minutes before serving. Garnish with chopped fresh parsley, if desired.