1. Preheat the oven to 425°F. Lightly grease a 2-quart baking dish with olive oil.

2. Bring a large pot of salted water to a boil. Cook the egg noodles according to package directions until al dente. Drain well and transfer to the prepared baking dish. Stir in the sour cream, Parmesan cheese, and 1/4 teaspoon of the salt until evenly combined.

3. In a large skillet, heat the olive oil over medium-high heat. Add the ground beef and cook, breaking it apart, until browned and fully cooked, about 4 minutes.

4. Stir in the chopped bell pepper and scallions. Cook for about 3 minutes, until slightly tender but still crisp.

5. Push the mixture to one side of the skillet. Add the tomato paste to the empty space and cook for 1 minute to deepen its flavor. Mix everything together.

6. Sprinkle in the Italian seasoning and remaining 1/4 teaspoon salt. Add the diced tomatoes with their juices. Stir well and bring to a gentle simmer. Cook for about 2 minutes, until slightly thickened.

7. Spoon the beef mixture evenly over the prepared noodles. Top with shredded Cheddar cheese.

8. Bake on the center rack for 15 to 20 minutes, until the cheese is melted and the edges are bubbling.

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