Preheat the oven to 200ºC/gas mark 6. Mix together the horseradish, breadcrumbs and parsley, season well and press onto the cod fillets.
Place on a baking sheet and bake for 10–12 minutes until the fish is cooked through. Serve with rocket salad and a wedge of lemon.
This topping works well with other fish such as haddock, salmon or mackerel fillet.