Preheat oven to 425 degrees F. In a shallow bowl, lightly beat the egg whites. In another shallow bowl, combine panko breadcrumbs, parmesan reggiano, smoked paprika, parsley flakes, and black pepper, mix well.

Dip each fillet in the egg, coating both sides, Drip of excess egg, then coat in the breadcrumb mixture, pressing the crumb mixture into both sides of the fish. Place the fillets in a large glass baking dish (you may need to use two dishes) sprayed with nonstick cooking spray. Bake in the preheated oven for 6-8 minutes per ½ inch thickness of fish, around 12 minutes, or until the flounder flakes easily with a fork.