Roast potato fish pie

Method

• step 1

  Heat the oven to 220C/200C fan/gas 7. Drizzle the oil over a large baking tray and slide into the oven to heat up. Tip the potatoes into a large pan, cover with water and season with salt. Bring to the boil, then reduce the heat and simmer for 8-10 mins. Drain and leave to steam-dry.

• step 2

  Carefully remove the baking tray from the oven and tip in the potatoes. Sprinkle with sea salt and black pepper and turn to coat in the oil. Roast for 35-40 mins until crisp, turning halfway through.

• step 3

  Meanwhile, make the filling. Melt the butter in a large saucepan over a medium heat and cook the shallots for 5 mins until softened. Pour in the wine and simmer for 2 mins until it has reduced. Sprinkle in the flour and stir until you have a paste.

• step 4

  Gradually whisk in the milk until you have a smooth sauce, then stir in the mustard and cream. Simmer for 2 mins, whisking occasionally. Tip in 100g of the cheese, the peas and fish pie mix, cover and cook for 8 mins more, stirring occasionally until the peas have defrosted and the fish is almost cooked through. Stir in the parsley and lemon zest and juice, then season to taste.

• step 5

  Pour the filling into a deep 20 x 25cm casserole dish and scatter the roasted potatoes over the top. Sprinkle with the remaining cheese. Turn down the oven to 200C/180C fan/gas 6 and bake the pie for 15-20 mins until the filling is bubbling at the edges. Serve with winter greens or a crisp salad.