Step 1 Bring a large pot of water to a boil and add chicken; continue to boil until no longer pink in the middle, 15 to 20 minutes. Let sit until cool enough to handle, then dice into small bite-sized pieces.
Step 2 While chicken cooks, bring a second large pot of lightly salted water to a boil. Cook elbow macaroni in the boiling water, stirring occasionally, until tender yet firm to the bite, about 8 minutes. Drain and rinse under cool water.
Step 3 At the same time, place eggs in a saucepan and cover with water. Bring to a boil, remove from heat, and let eggs stand in hot water for 15 minutes.
Step 4 Remove eggs from hot water and hold under cold running water to cool. Peel and dice eggs.
Step 5 Mix mayonnaise, sugar, vinegar, onion salt, salt, mustard, and pepper together in a large bowl. Mix in diced eggs, pasta, and chicken, adding a little more mayonnaise if too dry. Chill for at least 1 hour, or up to 8 hours or overnight before serving.
Note: If you want more flavor, add in your favorite fruit, veggie, or whatnot—such as celery, grapes, or frozen green peas.
