In a small bowl, whisk together mayonnaise, sour cream, Dijon mustard, and apple cider vinegar. Season with salt and pepper to taste. Set aside.

In a large mixing bowl, combine cooked pasta, diced chicken breast, crumbled bacon, halved cherry tomatoes, sliced red onion, chopped romaine lettuce, and shredded cheddar cheese. Stir gently to combine.

Pour the prepared dressing over the salad mixture and gently toss until everything is evenly coated with dressing.

Just before serving, gently fold in cubed toasted bread or croutons to maintain crunch.

Garnish with chopped parsley or chives and serve chilled or at room temperature.