Step 1

Preheat the oven to 180°C/ gas mark

Step 2

Wash and dice the potatoes and bring to the boil in a large saucepan of water. Reduce to a medium heat and cook until tender. Meanwhile, poach the fish. Peel and quarter the onion and put into a large sauté pan or saucepan with the thyme. Add the fish, cover with the milk, and poach on a low heat for around eight minutes. Remove the pan from the heat, take out the fish and onion pieces and place on a plate. Flake the fish with a fork. Reserve the poaching liquid to make the sauce with later. Boil or poach the eggs in a small saucepan for six minutes. Drain and carefully spoon on to the fish plate. Check the potatoes; they should be very soft by now. When cooked, drain the potatoes and tip back into the saucepan. Mash with a little milk and butter. Grate the cheese into the mash and stir well to melt through. Melt the butter in a milk pan over a low heat and add one tablespoon of the flour. Stir well with a wooden spoon to make a thick paste. Add the other tablespoon of flour and repeat. Now take a tablespoon of the reserved poaching liquid and stir it into the paste until well mixed in. Repeat, gradually adding more liquid, until blended together in a thick sauce. Add the spinach, stir to wilt, then tip in the cooked eggs, mashing them with the back of a fork to break up. Add the onion then the flaked fish and mix everything together well to coat in the sauce. Spoon the fish mixture into a large ovenproof casserole dish then top with the potato mash, starting at the edge of the dish and working inwards, using a fork to fluff up the top. Bake in the preheated oven for 20 minutes, until the mash is golden and crispy on top. Fill small freezer and ovenproof dishes half full with the fish mixture then top with the mash. Do not cook but instead allow to cool, cover and freeze for up to three months. To cook, remove from the freezer and bake straight from frozen in an oven preheated to 180°C/ gas mark 4 for 30 minutes.