Creating Beef Lombardi Casserole is quite simple when you follow these steps:

1. Cook the Pasta: Begin by cooking the elbow macaroni according to the package instructions until al dente. Drain and set aside.
2. Sauté Onions and Garlic: In a large skillet over medium heat, add the ground beef. Once browned, stir in the diced onion and minced garlic. Cook until the onion is translucent, about 3-5 minutes.
3. Season the Beef: Add Italian seasoning, salt, and pepper to the beef mixture. Stir well to combine.
4. Combine with Marinara: Pour in the marinara sauce and simmer for a few minutes. Make sure the mixture is evenly heated.
5. Mix with Pasta: In a large bowl, combine the cooked pasta with the beef mixture. Fold in ricotta cheese and half of the mozzarella and cheddar cheeses until evenly distributed.
6. Transfer to Baking Dish: Spread the mixture evenly into a greased casserole dish.
7. Top with Cheese: Sprinkle the remaining mozzarella and cheddar cheeses on top.
8. Bake: Preheat your oven to 350°F (175°C). Bake the casserole for 30-35 minutes or until the cheese is bubbly and golden brown.
9. Garnish: Remove from the oven and let it sit for about 5-10 minutes. Garnish with fresh parsley, if desired.

These steps will guide you to make an incredible Beef Lombardi Casserole that everyone will enjoy!