This was a bit of an experiment as I got home after work to find I had no butter in the fridge to make a roux. I was too tired to head back out, so I decided to experiment using olive oil. The result was a light and creamy white sauce that I’ll definitely make again.

The mash is “rustic” because I was lazy and didn’t bother skinning the potatoes – but I did take the time to add parmesan and yoghurt, which made all the difference.

For the pie filling

1-2 packs fish pie mix

1 onion, peeled and cut in half

One clove of garlic

500ml milk

2 dessertspoons olive oil

1 heaped dessertspoon plain flour

Salt, pepper

Vegetable of choice (I used leeks this time, but am also fond of peas for this recipe)

For the mash

500g potatoes, cleaned, chopped but unpeeled

2 tbsp natural yoghurt

25g parmesan, grated

Black pepper, nutmeg

Preheat your oven to 180C.

Place the fish in a saucepan with the garlic and onion and cover with milk. Simmer on a low heat until the fish is cooked through, then remove the fish from the milk and place in your baking dish (keep the milk, it is the base for your sauce. The onion and garlic can be saved for another recipe).

While the sauce is cooking, put your potatoes on to boil.

In a pan (I used the same one, so sue me!) heat the oil gently and stir in the flour to make a smooth paste. Cook for 1-2 mins before whisking in the milk in small amounts to form a lump-free sauce. Once you have added all the milk, add any uncooked veg and continue to simmer until the sauce thickens. Once this is done, you can pour the sauce over the fish and fold together gently.

Drain the potatoes and mash to your preferred consistency with the yoghurt and parmesan, adding black pepper and a dash of nutmeg. Place large spoonfuls of mash on top of the fish/sauce mixture. When the pie is completely covered, fluff the mash a little with a fork and then put in the oven and bake for 35-40 minutes.