Preheat the oven to 200C/Gas 6

Mix 100ml milk with the cornflour and set aside. Pour the rest of the milk into a large saucepan, add the haddock, cover and poach for 5 minutes.

Remove the fish from the liquid and flake, setting aside.

Add the cornflour mixture to the poaching liquid and bring to the boil, stirring continuously. Once thickened remove from the heat.

Stir 60g cheese, peas, haddock and macaroni into the sauce. Pour into an ovenproof dish and top with the rest of the cheese.

Bake for 20 minutes or until golden and bubbling.