Prepare chicken breasts by boiling in large pot of salted water. Drain. Let cool & chop or shred. (While chicken is cooling, prepare rest of ingredients.)
Cook pasta to al dente. Don't over cook. Drain and set aside.
In a large bowl, mix together chicken, celery and green onion.
Whisk together mayonnaise, lemon juice, pepper and parsley in a large measuring cup to create the dressing. Pour over top of chicken and mix until evenly coated.
Fold in grapes, pasta and sliced almonds, making sure all ingredients are evenly distributed. Top with extra cracked pepper, if desired and serve!