Mixture In a large mixing bowl, combine the ground beef, breadcrumbs, grated Parmesan cheese, milk, chopped onion, minced garlic, fresh parsley, fresh basil, dried oregano, salt, black pepper, red pepper flakes (if using), and beaten egg. Use your hands or a wooden spoon to mix the ingredients until well combined. Avoid overmixing, as it can result in a dense meatloaf.