Cook the pasta to al dente, following the directions on the package.
Drain and rinse under cold water, then let it completely cool.
Make the Dressing
In a large bowl, whisk the mayonnaise, caesar dressing, garlic powder, lemon juice, salt and pepper until smooth.
Assemble the Salad
Add the pasta, romaine, parmesan, chicken and tomatoes if using, tossing until everything is coated in the creamy dressing.
Taste and adjust the seasoning if needed.
Right before serving, fold in the croutons, and serve immediately, with extra Parmesan offered at the table.
Notes
Use a big bowl: The pasta and romaine need room for gentle tossing.
Stir the dressing first: The mayo and caesar dressing should be smooth before the pasta goes in.
Grate extra Parmesan: Mix some into the salad and sprinkle a little over the top before serving. I like to offer more at the table, as some people prefer more than others.