Preheat oven to 425 degrees F. Line a large baking sheet with parchment paper. Cut chicken into 1-inch pieces.
In a bowl whisk egg whites until frothy. In another bowl combine cheese, bread crumbs, and pepper.
Add chicken to egg whites; toss to coat. Transfer chicken, a few pieces at a time, to cheese mixture; toss gently to coat (if necessary, press lightly to adhere). Place chicken on the prepared baking sheet. Lightly coat chicken with cooking spray.
Bake 10 to 15 minutes or until chicken is no longer pink and coating is lightly browned. Serve marinara sauce with chicken for dipping.