Place the chicken, celery, grapes, cashews, curry powder, and salt in a large bowl. Toss to combine. Stir in the mayonnaise.
Cut croissants in half lengthwise. Place a leaf of green leaf lettuce on the bottom of each croissant half and top with chicken salad. Place the remaining croissant half on top. Serve immediately.
Notes
You can use either pre-cooked chicken from the store (such as rotisserie chicken) or cook chicken breasts from raw. You can make the salad up to 8 hours in advance of serving it. Do not freeze the salad—the mayonnaise with separate.Use roasted cashews if you can find them! If you use salted cashews, reduce the salt to one-half teaspoon and taste the salad for seasoning, adding more as needed. You can also substitute chopped almonds, pecans, or walnuts.