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

In a large mixing bowl, combine the cooked pasta, chicken breast, crispy bacon, cherry tomatoes, red onion, and romaine lettuce.

Drizzle the prepared dressing over the pasta mixture and toss everything together gently until all ingredients are coated.

Fold in the cubed toasted bread or croutons just before serving.

Garnish with fresh herbs if desired and serve chilled or at room temperature.