Begin by cooking the elbow macaroni according to the package instructions. When the macaroni is almost done, add the frozen green peas to the boiling water and cook them together for the remaining few minutes.

Once cooked, drain the macaroni and peas, and rinse them under cold water to stop the cooking process. Set them aside to cool.

In a large mixing bowl, combine the drained tuna, mayonnaise (or salad dressing), shredded Cheddar cheese (if using), sweet pickle relish (if desired), lemon juice, salt, and pepper. Stir everything together until well combined, creating a creamy and flavorful base for the salad.

Once the macaroni and peas have cooled down, add them to the bowl with the salad base. Gently fold the macaroni and peas into the creamy mixture until they are evenly coated. Be careful not to break the macaroni as you mix.

Now, it's time to add the chopped celery, crushed garlic, and chopped onion to the bowl. These crunchy and aromatic vegetables will add texture and depth of flavor to the salad. Mix everything together until the vegetables are evenly distributed throughout the salad.

Cover the bowl with plastic wrap or a lid and refrigerate the macaroni salad for at least 1 hour. Chilling allows the flavors to meld together and develop, resulting in a more delicious and cohesive salad.

Once chilled, give the macaroni salad a final stir before serving. Transfer it to a serving dish or individual plates, and garnish with a sprinkle of chopped parsley or additional shredded cheese if desired. Serve the Betty Crocker Tuna Macaroni Salad as a delightful side dish or a light meal option.

If you have any leftover macaroni salad, store it in an airtight container in the refrigerator for up to 2-3 days. Enjoy it cold or at room temperature as a tasty snack or meal accompaniment whenever hunger strikes.