1 cup panko breadcrumbs
3 tbsp melted unsalted butter
3 tbsp finely chopped fresh flat-leaf parsley
2 tsp finely grated lemon zest
kosher salt and freshly ground black pepper
six 1- to 1-1/2 inch thick cod fillets (about 6 oz. each)
Position a rack in the center of the oven and heat the oven to 425°F.
In a medium bowl, combine the panko, butter, parsley and lemon zest. Add a pinch of salt and a grind of pepper and stir to evenly distribute the ingredients.
Line a heavy-duty rimmed backing sheet with parchment. Arrange the cod fillets on the baking sheet and season all over with salt and pepper.
Divide the panko topping among the fillets, pressing lightly so it adheres. Roast until the breadcrums are browned and the fish is mostly opaque (just cooked through), with a trace of translucence in the center (cut into a piece to check), 10 to 12 minutes, depending on the thickness of the fillets. Serve immediately.