Heat oven to 450°F, line a 13-by-18-inch rimmed sheet with parchment and brush it with half the oil.
Cut cod into eight similar rectangular pieces and pat them very dry.
Place flour in one dish, whisk eggs with milk in another and combine cornflakes, breadcrumbs, paprika, salt and pepper in a third.
Coat each fish piece in flour, egg and crumbs, pressing firmly.
Arrange on the sheet, drizzle with remaining oil and bake for 8 minutes.
Turn carefully and bake 6 to 8 minutes more until crisp and the fish reaches 145°F.
Serve hot with tartar sauce.