Bring a large pot of salted water to a boil. Cook the pasta until al dente, according to package instructions. Drain into a colander. Rinse under cold water, then shake off as much excess water as possible. Set aside to cool.
Cut up some leftover cooked chicken breasts into bite-size pieces (or cook the chicken breasts according to this method for how to cook shredded chicken).
Shake out the pasta once more, then add the pasta to a large serving bowl. Top with the chicken, romaine, tomatoes, croutons, and Parmesan. Drizzle with Caesar dressing and toss to combine. Enjoy cold or at room temperature.
MAKE AHEAD: This salad can be made 1 day in advance.
TO STORE: Chicken Caesar pasta salad tastes best the day it is made but will keep in the refrigerator for 2 to 3 days and can be made 1 day in advance.
LEFTOVER TIP. Make a little extra dressing and set it aside to toss on the leftovers before serving to keep them from drying out. No extra dressing? Try reviving the leftovers with a big squeeze of lemon juice.