In a medium bowl, start by whisking together the Dijon mustard, fresh lemon juice, Worcestershire sauce, mayonnaise, minced garlic, and anchovy paste. Continue mixing until all the ingredients are well combined and the mixture is smooth. Finally, stir in the finely grated Parmesan cheese and black pepper, then set the dressing aside while you prepare the rest of the salad.
Bring a large pot of salted water to a rolling boil. Add your choice of pasta and cook according to the package directions, or until it is al dente, which typically takes about 10 minutes. Once cooked, drain the pasta thoroughly and transfer it to a large serving bowl to cool slightly.
Chop the hearts of Romaine into bite-sized, 1-inch pieces. Add the chopped lettuce and the shredded or chopped chicken to the large bowl with the cooked pasta. Pour the prepared Caesar dressing over the top of the ingredients in the bowl.
Gently toss everything together until the pasta, chicken, and lettuce are evenly coated with the creamy dressing. If you're using croutons, add them now, along with a garnish of extra Parmesan cheese. You can serve the salad immediately or cover and refrigerate it until you are ready to eat.