Creating Creamy Beef Alfredo Ziti Casserole is straightforward if you follow these steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Cook Pasta: In a large pot, cook the ziti pasta according to package instructions until al dente. Drain and set aside.
3. Brown the Beef: In a large skillet over medium heat, add the ground beef. Cook until browned, about 5-7 minutes. Drain excess fat.
4. Sauté Vegetables: Add the diced onion and minced garlic to the skillet. Sauté for 3-4 minutes until the onion is translucent.
5. Mix in Cream: Pour in the heavy cream and beef broth. Stir until well combined.
6. Add Cheese: Gradually add the grated Parmesan cheese, Italian seasoning, salt, and black pepper. Stir until the sauce is smooth and creamy.
7. Combine Pasta and Sauce: Add the cooked ziti pasta to the sauce, stirring until the pasta is well coated.
8. Transfer to Baking Dish: Pour the ziti mixture into a greased 9×13-inch baking dish.
9. Top with Mozzarella: Sprinkle the shredded mozzarella cheese evenly over the top.
10. Bake: Bake in the preheated oven for 30-35 minutes until bubbly and golden brown on top.
11. Garnish: Remove from the oven and sprinkle with fresh parsley if desired before serving.

These simple steps will guide you in creating an incredible Creamy Beef Alfredo Ziti Casserole that is sure to impress.