Preheat the oven to 350°F (175°C) and grease a 9x13-inch baking dish.
In a large bowl, combine the Italian bread crumbs, mozzarella cheese, salami, pepperoni, ham, green bell pepper, red onion, black olives, and Parmesan cheese. Mix well.
In a separate bowl, whisk together the eggs, milk, oregano, garlic powder, black pepper, and salt until well combined.
Pour the egg mixture over the bread crumb mixture and stir until everything is evenly coated.
Spread the mixture evenly in the prepared baking dish.
Bake in the preheated oven for 30-35 minutes, or until the top is golden brown and a toothpick inserted in the center comes out clean.
Allow to cool for 10 minutes before cutting into squares and serving.