Boil a large pot of salted water and cook pasta to al dente, according to package directions. Drain, rinse and set aside to cool.
In a large bowl, combine the mayonnaise, sour cream, blue cheese dressing and Dijon mustard. Season with fresh ground black pepper to taste. Pour in the cooled pasta and stir to coat.
Stir in the Romaine lettuce, chicken, tomatoes, green onions, hard boiled eggs, bacon (1 tablespoon reserved for topping), and about 3 ounces of blue cheese. Gently fold in the diced avocado.
Serve immediately, topped with remaining bacon and blue cheese crumbles for garnish, if desired. Or, chill in the fridge until ready to serve.
Notes
I absolutely love blue cheese, so I used the whole 4 ounces in my pasta salad. However, if you want a milder tasting salad, add half of the cheese, then taste, and add more if you wish.Store in a tightly sealed container. You can make the salad a day in advance and store leftovers up to 3-4 days.Make Ahead up to 24 hours in advance. I recommend waiting until just before serving to slice and add the avocado to avoid it turning brown.