If you love casserole for breakfast and have some leftovers in your fridge, here is a leftover LeftLover Pizza Breakfast Casserole recipe!
Preheat oven to 175 degrees C. Spray a baking dish with cooking spray.
Arrange pizza squares in the prepared baking dish. Mix eggs, milk, mozzarella cheese, onion, butter, garlic, oregano, and salt in a large bowl; pour over pizza pieces. Top with Parmesan cheese and red pepper flakes. Cover the dish with foil.
Bake in the preheated oven for 45 minutes. Remove foil and continue baking until eggs are set and Parmesan cheese is melted about 20 more minutes.