Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish with cooking spray or olive oil.

In a large bowl, combine the sliced zucchinis, garlic, salt, black pepper, and Italian seasoning. Toss to coat the zucchini evenly.

In another bowl, mix together the beaten eggs, cheddar cheese, mozzarella cheese, and half of the Parmesan cheese. Stir until well combined.

Add the zucchini mixture to the cheese mixture and stir until the zucchini is evenly coated.

Pour the mixture into the prepared baking dish, spreading it out evenly.

In a small bowl, combine the breadcrumbs, remaining Parmesan cheese, and chopped parsley. Sprinkle this mixture evenly over the zucchini bake.

Drizzle the olive oil over the top of the breadcrumbs to help them brown.

Bake in the preheated oven for 30-35 minutes, or until the top is golden brown and the zucchini is tender.

Let it cool for about 5 minutes before serving.