Preheat your oven to 350°F (175°C).

Chop the fresh spinach into small pieces and set aside.

In a large mixing bowl, combine the chopped spinach with the ricotta cheese, shredded mozzarella cheese, grated Parmesan cheese, and softened cream cheese. Add the eggs, milk, garlic powder, onion powder, salt, black pepper, and red pepper flakes. Mix until well combined.

Grease a 9x9-inch baking dish and spread the spinach and cheese mixture evenly into the dish. Sprinkle breadcrumbs over the top.

Bake the casserole for 30-35 minutes, or until set and golden brown. Let it cool for 5 minutes before serving.