Creating the perfect Spaghetti Casserole involves following these straightforward steps:

1. Preheat the Oven: Begin by preheating your oven to 350°F (175°C).

2. Cook the Spaghetti: In a large pot of salted boiling water, cook the spaghetti according to package directions until al dente. Drain and set aside.

3. Brown the Meat: In a large skillet over medium heat, sauté the chopped onion until translucent, about 5 minutes. Add the minced garlic and ground meat, cooking until the meat is browned. Season with salt, pepper, and Italian seasoning.

4. Combine Sauce and Meat: Stir in the marinara sauce, mixing well. Let it simmer for a couple of minutes to blend the flavors.

5. Mix the Cheeses: In a separate bowl, combine the ricotta cheese with half of the mozzarella and half of the Parmesan cheese. Stir until smooth.

6. Layer the Ingredients: In a casserole dish, start by layering half of the spaghetti. Top it with half of the meat sauce. Spread the cheese mixture over the meat sauce, then repeat the layers, finishing with the remaining meat sauce on top.

7. Add Remaining Cheese: Sprinkle the remaining mozzarella and Parmesan on top of the casserole.

8. Bake: Place the dish in the preheated oven and bake for 30-35 minutes, or until the cheese is bubbly and golden.

9. Cool and Serve: Once done, remove from the oven and let it cool for a few minutes. Garnish with fresh basil or parsley, if desired.

10. Enjoy: Serve warm and enjoy the amazing flavors that your efforts have brought forth.