In a medium bowl, whisk together mayonnaise, sour cream, Dijon mustard, apple cider vinegar, salt, and black pepper until smooth.

In a large mixing bowl, combine the cooked pasta, shredded chicken, crispy bacon, halved cherry tomatoes, finely chopped red onion, chopped romaine lettuce, and shredded cheddar cheese.

Pour the creamy dressing over the pasta mixture and toss until everything is well coated.

Fold in the cubed toasted bread or croutons before serving.

Sprinkle freshly chopped parsley or chives over the top and serve chilled.