2 cups buttermilk
4 skinless, boneless chicken breast halves, cut into bite-size pieces
2 1/2 cups panko bread crumbs
6 tablespoons grated Parmesan cheese
1 tablespoon onion powder
2 teaspoons garlic powder
1 teaspoon ground black pepper
1 teaspoon cayenne pepper (optional)
1 teaspoon paprika
Stir buttermilk and hot sauce together in a bowl; add chicken and stir to coat. Marinate chicken in refrigerator at least 1 hour.
Lightly grease a baking sheet.
Mix panko bread crumbs, Parmesan cheese, onion powder, garlic powder, cayenne pepper, and paprika in large shallow bowl.
Remove chicken from marinade, shaking pieces to remove excess moisture. Discard the remaining marinade.
Gently press chicken pieces into the panko mixture to coat. Gently toss between your hands so any bread crumbs that haven't stuck can fall away. Arrange breaded chicken onto prepared baking sheet.
Refrigerate breaded chicken at least 30 minutes.
Preheat oven to 400 degrees F (200 degrees C).
Lightly coat chicken pieces with cooking spray.
Bake chicken in preheated oven until browning on top, 15 to 20 minutes. Flip pieces and continue baking until the chicken is cooked through and the coating is crisp, 15 to 20 minutes more.