Creating Cheesy Hamburger Casserole is straightforward if you follow these simple steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C).
2. Cook the Pasta: In a pot of boiling salted water, cook the pasta according to package instructions until al dente. Drain and set aside.
3. Brown the Beef: In a large skillet, brown the ground beef over medium heat. Drain excess fat.
4. Add Onions and Garlic: Add the diced onion and minced garlic to the skillet. Sauté until the onion is translucent.
5. Combine Ingredients: Stir in the diced tomatoes with their juice, tomato sauce, and Italian seasoning. Season with salt and pepper.
6. Mix in Pasta: Add the cooked pasta to the meat mixture. Stir in 1 cup of cheddar cheese and the sour cream until everything is well combined.
7. Transfer to Baking Dish: Pour the mixture into a greased 9×13-inch baking dish, spreading it evenly.
8. Top with Cheese: Sprinkle the remaining ½ cup of cheddar cheese and the mozzarella cheese over the top.
9. Bake: Place in the preheated oven and bake for 25-30 minutes or until cheese is bubbly and slightly golden.
10. Cool and Serve: Remove from the oven and allow it to cool for about 5-10 minutes before serving.

Following these steps will allow you to create a comforting and delicious casserole that everyone will adore.