01 -
Whisk half-and-half, mayonnaise, grated onion, dark brown sugar, salt, and black pepper in a medium bowl until smooth. Refrigerate until needed.
02 -
Boil macaroni according to package directions plus an additional 5 minutes for softness. Drain and return macaroni to pot. Stir in apple cider vinegar and cover. Let sit at room temperature for 20 minutes.
03 -
Add half of the dressing to the macaroni and mix thoroughly. Cover and cool for 20 minutes at room temperature.
04 -
Add remaining dressing, sliced green onions, chopped celery, and grated carrots. Stir well and season with salt and pepper as needed. Let cool to room temperature for about 30 minutes.
05 -
Transfer salad to a serving bowl, cover with plastic wrap, and refrigerate for at least 2 hours before serving to allow flavors to meld.