Preheat oven to 375°F (190°C) and line a baking sheet with parchment paper or aluminum foil. Spray with cooking spray or brush with some oil.
In a blender or food processor, pulse the walnuts until they are finely chopped. Add the parmesan cheese, lemon zest, parsley, dill, salt, and pepper and pulse until well combined. Transfer the mixture to a small bowl and set aside.
Place the cod fillets on the prepared baking. Pour the melted butter on top of the fish and evenly coat each one. Sprinkle the parmesan walnut mixture evenly over the top of the fish, pressing lightly to adhere.
2 Cod Fillets
Bake for 15 minutes or until the fish flakes easily with a fork and the crust is golden brown. Serve hot with some lemon wedge and tartar sauce if desired.
The best way to tell if the fish is done is to use a fork and gently flake the thickest part of the fillet. If it flakes easily and is opaque and moist, it is done. You can also use a meat thermometer and check the internal temperature of the flaky fish. It should be at least 145°F (63°C) for safety.
How do I store and reheat the leftovers?
You can store the leftovers in an airtight container in the refrigerator for up to 2-3 days. To reheat, you can microwave them for a few seconds or bake them in a 350°F (177°C) oven for 10 minutes or until heated through. You can also freeze the leftovers for up to 3 months and thaw them in the refrigerator before reheating.