Step 1: Preheat the Oven

Preheat your oven to 375°F (190°C). Grease a 9×13-inch baking dish with nonstick spray or butter and set aside.

Step 2: Cook the Pasta

1. Bring a large pot of salted water to a boil.
2. Cook the pasta according to the package instructions until al dente. Drain and set aside.

Step 3: Prepare the Ground Beef Mixture

1. In a large skillet, cook the ground beef over medium heat until browned and fully cooked. Drain excess fat if necessary.
2. Add the chopped onion and minced garlic to the skillet. Cook for 2-3 minutes until the onion is softened and fragrant.
3. Stir in the diced tomatoes, tomato sauce, Italian seasoning, smoked paprika, salt, and black pepper. Let the mixture simmer for 5 minutes, allowing the flavors to meld.
4. Remove from heat and set aside.

Step 4: Make the Cheese Sauce

1. In a medium saucepan, melt the butter over medium heat.
2. Whisk in the flour and cook for 1-2 minutes to create a roux, stirring constantly to avoid burning.
3. Gradually pour in the milk, whisking continuously to prevent lumps.
4. Cook the mixture for 3-5 minutes, or until it thickens.
5. Remove from heat and stir in the shredded cheddar and Monterey Jack cheeses until melted and smooth.

Step 5: Assemble the Casserole

1. In a large mixing bowl, combine the cooked pasta, ground beef mixture, and cheese sauce. Mix until evenly coated.
2. Transfer the mixture to the prepared baking dish, spreading it out evenly.
3. Top with shredded mozzarella, Parmesan, and breadcrumbs if using.

Step 6: Bake the Casserole

1. Place the casserole in the preheated oven and bake for 20-25 minutes, or until the cheese is bubbly and golden.
2. If a crispier topping is desired, broil for an additional 2-3 minutes.

Step 7: Serve and Enjoy

1. Remove the casserole from the oven and let it rest for 5 minutes before serving.
2. Garnish with chopped parsley or your favorite herbs. Serve hot.