1. Preheat your oven to 350°F (175°C). Lightly grease a 9×13 inch baking dish.

2. In a large skillet, cook the ground beef over medium-high heat until browned. Drain off any excess fat.

3. Add the chopped onion and bell pepper to the skillet and cook for 5-7 minutes, until softened. Stir in the minced garlic and cook for 1 more minute until fragrant.

4. In a large mixing bowl, combine the cooked ground beef mixture, the cooked pasta, the undrained diced tomatoes, the cream of mushroom soup, and half of the shredded cheese (1/2 cup).

5. Stir in the Italian seasoning, and season with salt and pepper to taste. Mix everything together until well combined.

6. Pour the mixture into the prepared baking dish and spread into an even layer.

7. Sprinkle the remaining 1/2 cup of cheese over the top.

8. Bake, uncovered, for 25-30 minutes, or until the casserole is hot, bubbly, and the cheese is golden brown.

9. Let the casserole rest for 10 minutes before serving.