Olive oil spray
2 1/2 ounces boneless, skinless chicken breast
2 teaspoons unbleached or all-purpose flour
1/2 teaspoon sugar
1/4 teaspoon salt plus more to taste
1/2 teaspoon ground black pepper plus more to taste
1/8 teaspoon onion powder
2 egg whites
2 tablespoons fat-free milk
3/4 cup panko (Japanese bread crumbs, available in the Asian foods aisle)
Preheat the oven to 475°F. Lightly mist a nonstick baking sheet with olive oil spray. Set aside. Place the chicken breast on a cutting board. Cover with a sheet of waxed paper. With the smooth side of a meat mallet, pound to an even 1/4-inch thickness. Cut into 25 pieces that are all roughly the same size.
In a resealable plastic bag, combine the flour, sugar, 1/4 teaspoon salt, 1/2 teaspoon pepper and the onion powder. Shake to mix well. Add the chicken pieces to the bag. Shake to completely coat the chicken with the flour mixture. Set aside.
In a small shallow bowl, combine the egg whites and the milk. Beat with a fork until smooth. Place the panko on a small sheet of waxed paper set next to the egg-white mixture.
One at a time, dip the chicken pieces into the egg-white mixture, being sure to coat completely. Allow any excess egg-white mixture to drip off. Dip into the panko to coat completely. Dip again into the egg-white mixture, then the panko. Drop the pieces on the baking sheet and arrange to avoid their touching. Lightly mist with olive oil spray. Season to taste with salt and pepper.
Bake for 5 minutes. Carefully flip the chicken. Bake for 5-7 minutes longer, or until the breading is crunchy but not browned and the chicken is no longer pink inside.