Season the cod well with salt and pepper to taste.
Mix the breadcrumbs with the parsley, garlic, lemon zest, salt and pepper, then add the butter and lemon juice. Mix thoroughly with your fingers.
Place the cod in a shallow, ovenproof dish and press the buttered crumbs firmly onto the cod to make an even crust.
Bake at 220°C/Gas 7 for 20-25 minutes until the crust is browned and the fish just cooked through. Serve immediately with lemon wedges and green salad or steamed asparagus and new potatoes.