Ultimate Creamy Fish Pie

While the potatoes cook, trim the root and dark green leafy part from the leek and discard. Halve lengthways, then thinly slice. 

Heat a drizzle of oil in another large saucepan on medium-high heat.

Once hot, add the leek and season with salt and pepper. Cook, stirring occasionally, until softened, 4-6 mins.

Meanwhile, peel and grate the garlic (or use a garlic press). Drain the fish pie mix and pat dry with kitchen paper. IMPORTANT: Wash your hands and equipment after handling raw fish.

Once the leek has softened, add the garlic and cook for 30 secs more.

Add the butter (see pantry for amount) and allow it to melt, then stir in the flour (see pantry for amount). Cook, stirring continuously, for 1-2 mins. 

Stir in the water for the sauce (see pantry for amount) a little at a time, followed by the vegetable stock paste. Bring to the boil, then simmer, stirring occasionally, until thickened, 2-3 mins.

Once the sauce has thickened, stir in the creme fraiche, wholegrain mustard and half the hard Italian style cheese.

Next, gently stir through the fish pie mix.

Lower the heat and simmer gently, stirring occasionally, until the fish is cooked, 5-8 mins. IMPORTANT: The fish is cooked when opaque in the middle.

Meanwhile, heat your grill to high. 

Once the potatoes are cooked, drain in a colander and return to the pan, off the heat. Add a knob of butter and a splash of milk (if you have any) and mash until smooth. Season with salt and pepper. 

Once the fish is cooked, stir through the peas. Cook until piping hot, 1-2 mins. Season with salt and pepper, then transfer to an ovenproof dish. 

Using a fork, spread the mash evenly over the filling, then sprinkle over the remaining cheese.