Preheat oven to 400 degrees F. Spray rimmed baking pan with cooking spray. In food processor fitted with knife blade attachment, pulse cashews until finely ground.
Place ground cashews in shallow dish. Add breadcrumbs, salt, and pepper; stir until well combined. In second shallow dish, whisk eggs. Working with one piece at a time, dip chicken in egg, shaking off excess; then dip in cashew mixture. Place on prepared baking pan; lightly spray chicken with cooking spray. Transfer chicken to 400-degree oven and bake 18 to 20 minutes or until internal temperature reaches 165 degrees F, turning once.
Meanwhile, make the couscous: Prepare couscous according to package directions. Stir in mint and parsley.
To make the salad, in a large bowl, toss arugula, grapefruit, and oil until well combined.
Divide couscous between four plates. Place chicken over couscous and top with salad.