Step 1

Bring a large pot of salted water to a roiling boil. Add macaroni and cook until very soft, 10 to 12 minutes. Drain, return the pasta to the pot and immediately toss with vinegar. Let cool ten minutes.

Step 2

In a large bowl, whisk together 1 cup of the mayonnaise, 1 1/2 cups of the whole milk, the brown sugar, salt, and pepper.

Step 3

Once the macaroni has cooled for 10 minutes, toss with the mixed sauce and let cool to room temperature.

Step 4

Once cool, fold in the scallion, carrot, and celery. Whisk together the remaining 1 cup mayonnaise and 1/2 cup whole milk and pour over macaroni salad. Toss well to coat. Taste and add more salt or pepper as needed.

Step 5

Chill in the refrigerator until cold.