Prep the chicken. If using rotisserie chicken, remove skin and bones, then chop or shred into bite-size pieces. Aim for small, even pieces so the salad holds together.

Make the dressing. In a large bowl, whisk together mayonnaise, Greek yogurt, Dijon mustard, lemon juice, a pinch of salt, and a few grinds of pepper. You want a creamy, spoonable texture. Adjust lemon and Dijon to taste.

Add the crunch. Stir in chopped celery, minced onion, and fresh herbs. This builds flavor and keeps each bite lively.

Fold in the chicken. Add the chicken and gently combine until everything is evenly coated. Taste and season again with salt and pepper.

Add sweetness and texture. Fold in halved grapes and, if using, toasted nuts or dried cranberries. Mix gently so the grapes don’t break down.

Chill briefly. Cover and refrigerate for 20–30 minutes. This lets the flavors mingle and helps the salad set.

Prep the croissants. Split the croissants horizontally. For extra texture, lightly toast the cut sides in a dry skillet for 1–2 minutes until just crisp.

Assemble. Add a few lettuce leaves to the bottom half, spoon on a generous mound of chicken salad, and top with the other half of the croissant. Serve right away.