A Pie That Earns Its Space in the Freezer

There are few things more comforting on a grey Tuesday in February than a fish pie pulled from your own freezer, still bubbling at the edges, with a golden mash lid that crackles under the fork. It is the sort of dinner that feels like an occasion but costs you almost nothing in effort on the night, because the work was done three weeks earlier on a quiet Sunday afternoon.

The trick is to build the pie so that it freezes properly. That means a sauce thick enough not to split, fish that has been gently poached rather than boiled, and mash with enough butter and cheese in it to come back to life rather than turn watery. Get those three things right and you can portion this into individual trays and eat well for a month.

Choosing the Fish and Poaching It Gently

You want about 700g of boneless white fish and 250–300g of raw king prawns. Haddock and cod are the classics, but pollock is cheaper and takes to this treatment beautifully, and a mix of two or three different fish gives a better texture than a single variety. Smoked haddock, even 200g of it, lifts the whole pie enormously, so use it if you can find undyed fillets.

Put the white fish in a wide pan, cover with 500ml of whole milk, and add a bay leaf, six black peppercorns, a few strips of lemon zest and a small handful of parsley stalks. Bring just to a bare shiver over a low heat, then take the pan off the hob and let the fish sit in the hot milk for eight to ten minutes. It will finish cooking through in the residual heat. Lift it out with a slotted spoon onto a plate, and keep every drop of that milk — it is the backbone of your sauce.

Flake the fish into large chunks once it is cool enough to handle. Chunks, not shreds; you want to recognise it later.

The Parsley Sauce, and Why It Must Be Thick

Melt 50g of butter in a heavy saucepan, stir in 50g of plain flour and cook it over a low heat for two minutes until it smells biscuity rather than raw. Add the reserved poaching milk a ladleful at a time, whisking hard after each addition so no lumps form. You should end up with a sauce the consistency of thick double cream — noticeably thicker than you would serve on its own, because the fish and prawns will release moisture as the pie bakes.

Off the heat, stir in a heaped teaspoon of English mustard, a good grating of nutmeg, a squeeze of lemon juice, 50g of grated mature cheddar and three or four tablespoons of chopped flat-leaf parsley. Season firmly. Fold through the flaked fish and the raw prawns — they will cook through when the pie is reheated — then taste again and adjust the lemon and salt. Spread this into your containers while it is still warm, but let it cool completely before the mash goes on.

Cheesy Mash That Survives the Freezer

Use floury potatoes: Maris Piper, King Edward or Rooster. Peel and cut 1.2kg into even chunks, boil in salted water until a knife slides in easily, then drain and leave them in the colander for a couple of minutes to steam dry. This step matters more than people think — wet potatoes give you wet mash, and wet mash weeps into the sauce on reheating.

Mash them thoroughly, then beat in 100g of butter, 100ml of warm milk and 100g of grated mature cheddar. A tablespoon of double cream or a spoonful of cream cheese helps the mash freeze and thaw with a softer texture. Season with plenty of salt, white pepper and a little nutmeg. The mash should be looser than you would serve on a plate, but still hold its shape on a spoon.

• Do not use a food processor for the mash — it turns gluey.
• Do let the fish base cool fully before topping, or steam will make the mash soggy.
• Do spread the mash right to the edges of the container to seal the filling in.

Assembly, Portioning and Freezing

Individual foil trays are the practical choice: they stack neatly, reheat evenly and mean you can cook two portions on a night when only two of you are eating. Ladle the fish mixture into the trays, leaving a good centimetre of headroom, then spoon or pipe the mash on top and rough it up with a fork — those ridges are where the colour and crunch come from.

For a little extra, scatter over 30g of grated cheddar mixed with a handful of panko or stale breadcrumbs. Cool the pies completely, ideally within ninety minutes of assembling, then cover with cling film pressed to the surface, or with a lid, label with the date and freeze. They will keep well for up to three months.

If you would rather make one large family pie, use a 1.5-litre dish and follow the same timings below, adding ten minutes.

Reheating from Frozen

You can cook these straight from frozen — no thawing, no faff. Heat the oven to 200°C fan (220°C conventional, gas mark 7). Put the trays on a baking sheet and bake for 45 to 50 minutes, until the filling is bubbling at the edges and the mash is deeply golden. If the top is colouring too quickly, lay a piece of foil loosely over it.

Individual pies can also be microwaved from frozen for six to seven minutes, then flashed under a hot grill for three or four minutes to crisp the top. Let them stand for five minutes before eating, and serve with something sharp and green — buttered garden peas with mint, or simply steamed purple sprouting broccoli with lemon. A slice of thick, buttered white bread on the side is not excessive; it is correct.