Panko bread crumbs are created by first passing an electric current through bread dough, which results in bread with no crust. Once cooked, the bread is shredded into large flakes that keep their shape and do not absorb as much oil as traditional Western bread crumbs do. This creates a light, crunchy crust for baked fish, giving you the satisfying crispness of a fried fillet without requiring you to stand over a pan of hot oil.
Preheat your oven to 450 degrees Fahrenheit.
Coat a baking dish with nonstick cooking spray.
Season your fish on both sides with salt and pepper. Use seasoned salt and lemon pepper, or salt-free seasoning if you are limiting your salt intake.
Crack a fresh egg into a pie plate or other wide, shallow dish.
Add about 1/2 inch of milk. If you are making more than four to six fillets, you may need to add another 1/4-inch or so of milk.
Beat the egg into the milk with a fork or whisk until the mixture is creamy and smooth.
Fill a second pie plate with a thick layer of panko bread crumbs.
Dip a piece of fish into the mixture of egg and milk. Let the excess drip off.
Coat both sides of the fish with panko bread crumbs. Place the coated fish into the greased baking dish. Repeat until all of the fish is coated and placed in the baking dish.
Dot the top of the fish with two to three paper-thin slices of butter.
Bake the fish for 10 minutes per every inch of thickness. For example, if your fish is 1/2 inch thick, bake it for 5 minutes.
Turn it halfway through its total cooking time if you like, although this is not strictly necessary.
Insert an instant-read thermometer into the thickest piece of fish to ensure that it has reached its safe internal temperature of 145 degrees Fahrenheit.