Put the haddock, milk and seasoning into a saucepan and simmer gently for 10-15 minutes until the haddock is tender. Drain, reserving the milk, and skin and flake the fish. Put the haddock, eggs and onion into a shallow ovenproof dish.

Melt 15 g (1/2 oz) margarine in a saucepan, stir in 15 g (1/2 oz) flour and cook for 1 - 2 minutes. Remove from the heat. Make the reserved milk up to 300 ml (1/2 pint) with a little more milk, if necessary, and gradually stir into the flour mixture. Return to the heat and bring to the boil, stirring. Cook for a further 1-2 minutes until thick. Season, then stir into the fish mixture.

To make the crumble topping, rub the remaining margarine into the remaining flour until the mixture resembles breadcrumbs, then stir in the oats. Sprinkle the topping over the fish mixture and bake in the oven at 190°C (375°F) mark 5 for 20 minutes until golden brown. Garnish with chopped parsley.