01 - Bring a large pot of salted water to a rolling boil. Add elbow macaroni and cook until very soft, approximately 1-2 minutes beyond the al dente package directions. Drain thoroughly and let cool slightly.
02 - In a large mixing bowl, whisk together mayonnaise, whole milk, apple cider vinegar, granulated sugar, salt, and black pepper until completely smooth and well incorporated.
03 - Add the slightly warm macaroni to the prepared dressing. Toss vigorously to ensure every piece is thoroughly coated with the creamy mixture.
04 - Stir in grated carrots, chopped celery, onion, and green onions. Mix until all ingredients are evenly distributed throughout the salad.
05 - Cover the bowl and refrigerate for at least 2 hours. For optimal flavor development and texture, refrigerate overnight before serving.
06 - Before serving, taste and adjust seasoning if needed. If the salad appears too thick, add additional mayonnaise or milk to achieve desired creaminess.