Cook the pasta: Bring a large pot of salted water to a boil. Cook pasta until just al dente, 1 minute less than package directions. Drain, rinse briefly under cool water to stop cooking, and toss with a drizzle of olive oil so it doesn’t stick.
Season and cook the chicken: Pat chicken dry.
Season with salt, pepper, and a little garlic powder if you like. Sear in a hot skillet with olive oil until golden and cooked through, then rest and slice. Or shred a rotisserie chicken to keep it simple.
Prep the greens and add-ins: Chop romaine into bite-size pieces.
Halve cherry tomatoes and thinly slice red onion if using. Grate or shave the Parmesan.
Make or stir the dressing: If using store-bought, taste and adjust with a squeeze of lemon and black pepper. For a quick homemade version, whisk mayo, lemon juice, Dijon, minced garlic, Worcestershire, anchovy paste (optional), olive oil, and grated Parmesan.
Season to taste.
Toss the pasta and chicken: In a large bowl, combine cooled pasta and chicken. Add half the dressing and toss well to coat. This helps the flavors soak into the pasta.
Add the crunch: Gently fold in romaine, tomatoes, and red onion.
Add more dressing until everything is lightly coated but not soggy.
Finish and serve: Top with croutons right before serving so they stay crisp. Shower with extra Parmesan, lemon zest, and fresh cracked pepper. Taste and adjust salt and acidity.