Bring a large pot of well-salted water to a boil. Add the pasta and cook until al dente, about 8 to 10 minutes. Drain and rinse immediately under cold running water to stop the cooking and cool the pasta down. Set aside in a colander to drain fully.

In a small bowl, whisk together the Greek yogurt, olive oil, lemon juice, Dijon mustard, minced garlic, anchovy paste (if using), and grated Parmesan until smooth and creamy. Season with salt and black pepper. Adjust thickness with a splash of water or lemon juice if too thick, or more Greek yogurt if too thin.

Chop the cooked chicken breast into bite-sized pieces and the romaine lettuce into roughly 1-inch chunks. Prep any optional add-ins like cherry tomatoes or cucumbers.

In a large bowl, combine the cooled pasta, chopped chicken, and romaine. Pour the dressing over and toss gently until everything is evenly coated. Taste and adjust seasoning. Add the garlic croutons and toss once more. Reserve a handful of croutons for garnish on top.

Serve immediately for the best crunch, or divide into airtight containers for meal prep. Always add croutons just before eating to keep them crispy.