Boil 2 cups of rotini pasta according to package directions until just barely tender—I use 12 minutes for regular pasta. Drain completely but don't rinse; the starch helps dressing adhere.

While pasta cooks, whisk together 2 tbsp olive oil, 2 tbsp lemon juice, 1 tsp Dijon mustard, salt, and pepper in a large bowl. I do this while standing at the stove so I'm ready the moment pasta drains.

Transfer warm pasta directly to the dressing and toss for 1-2 minutes, coating every piece. This is the step most recipes skip, and it's why your filling summer pasta family version stays flavorful instead of dull—warm pasta absorbs seasoning better than cold.

Let pasta sit in dressing for 5 minutes before adding anything else. I set a timer because my brain always wants to rush ahead here.

Fold in 2 cups diced cooked chicken, then add cherry tomatoes, cucumber, red onion, olives, and mozzarella last. Work gently so you don't crush the vegetables or break apart the cheese shreds—this matters more than you'd think.

Stir in 1/4 cup fresh parsley just before serving. Fresh herbs bruise quickly when mixed too early, which turns them gray and bitter instead of bright.

Taste and adjust seasoning—sometimes the lemon intensifies as the chicken pasta salad family summer sits, so hold back on extra salt until you check first.