Cook the pasta: Bring a large pot of salted water to a boil. Add the pasta and cook until al dente, following the package time. Drain well.

Cool and toss with oil: Spread the pasta on a sheet pan or in a large bowl to cool slightly. Drizzle with a little olive oil and toss so it doesn’t stick.

Prep the mix-ins: While the pasta cools, cook the bacon until crisp, then crumble. Chop the chicken and romaine. Halve the cherry tomatoes. Slice the onion if using. Grate the Parmesan.

Start the base: In a big mixing bowl, add the pasta, chicken, bacon, tomatoes, onion, and about half the Parmesan. Season lightly with salt and pepper.

Add the dressing: Pour in about 3/4 cup of Caesar dressing and toss gently to coat. Add more dressing as needed until everything is nicely coated but not soupy.

Fold in the lettuce: Add the chopped romaine and toss again, just enough to distribute without bruising the leaves.

Finish and taste: Squeeze half a lemon over the salad, add a bit more black pepper, and taste. Adjust salt, pepper, and lemon as needed. Stir in crushed croutons if serving right away, or save them for the top.

Garnish and serve: Sprinkle the remaining Parmesan over the top and add extra croutons for crunch. Serve chilled or at cool room temperature.