Authentic Hawaiian Macaroni Salad

My Mom's favorite macaroni salad that is so delicious and creamy!

Authentic Hawaiian Macaroni Salad

2 cups 2% or whole milk, divided
2 cups mayonnaise, divided
1 TBSP. brown sugar
1 tsp. salt
freshly ground black pepper to taste
1 lb. elbow macaroni
1/4 cup cider vinegar
1/4 cup finely grated yellow onion
1/2 cup finely shredded carrot
1/2 cup finely chopped celery

In small bowl, whisk together 1 1/2 cups milk, 1 cup mayonnaise, brown sugar, salt and pepper. Set aside.
In a large pot, bring 4 quarts water to boil. Add 1 TBSP. salt and pasta to water and cook to package directions. Drain pasta and pour into large glass bowl. Stir in vinegar and mix well until distributed and absorbed. Let pasta cool 10 minutes. Stir in the milk/mayo mixture and stir to evenly combine. Then let cool completely.
Once cool, stir in onions, carrots and celery. Add remaining milk and mayonnaise and mix until evenly distributed. Cover and chill for at least 1 hour for up to 2 days. Adjust seasonings and serve.
(**if you prefer a sweeter style macaroni salad, increase brown sugar up to 1/2 cup)