Boil the pasta: Bring a large pot of salted water to a boil. Cook macaroni until just past al dente, about 1 minute longer than package directions, so it stays tender when chilled.

Rinse and cool: Drain the pasta and immediately rinse under cold water to stop cooking and remove excess starch. Shake off well so it isn’t watery.

Mix the dressing: In a large bowl, whisk together mayonnaise, sour cream, Dijon, vinegar, sugar, celery seed, salt, and pepper until smooth and glossy.

Add the veggies: Stir in peas, celery, bell pepper, onion, relish, and dill. This builds flavor into the dressing before the pasta goes in.

Fold in pasta and eggs: Add cooled macaroni and chopped eggs. Gently fold until everything is evenly coated. If adding ham or cheddar, fold them in now.

Taste and adjust: Add a pinch more salt, pepper, or vinegar if needed. If it looks dry, stir in 1–2 tablespoons of milk or an extra spoonful of mayo.

Chill: Cover and refrigerate for at least 1 hour (2–4 hours is better). The flavors meld and the pasta absorbs some dressing.

Serve: Stir just before serving and garnish with extra dill, a sprinkle of paprika, or a few slices of egg on top for a festive touch.