Directions

1. 1

   Wash your hands thoroughly with soap and warm water before beginning.

2. 2

   Bring a large pot of salted water to a boil. Add pasta shells and cook according to package directions until al dente. Drain well in a colander and set aside.

3. 3

   Heat the vegetable oil in a large skillet over medium heat. Add the chopped onion and green bell pepper, and sauté for 4–5 minutes, stirring occasionally, until softened and fragrant.

4. 4

   Stir in the cream of mushroom soup, ensuring it is well blended with the vegetables. Add the canned diced tomatoes with their liquid and the drained tuna. Stir gently to combine all ingredients and heat through, about 2–3 minutes.

5. 5

   Add the cooked pasta to the tuna and vegetable mixture. Fold together gently until the pasta is evenly coated with the sauce.

6. 6

   Transfer the pasta mixture to a 9-by-13-inch baking dish, spreading it in an even layer.

7. 7

   Cover the baking dish with foil and bake at 350°F for 25 minutes, or until the mixture is hot and bubbling around the edges.

8. 8

   Remove the foil. If using cheese and parsley, sprinkle the shredded cheese evenly over the top and return the casserole to the oven for 5 minutes, until the cheese is melted. Garnish with fresh parsley before serving if desired.