Chicken and broccoli pie

Method

1. Preheat the oven to 200°C/fan180°C/gas 6. Melt 25g of the butter in a large frying pan, add the onion and cook slowly for 15 minutes or until softened and caramelised. Remove from the heat and set aside.
2. Steam the broccoli for 3-4 minutes until al dente, refresh in a bowl of iced water, then drain.
3. Melt the remaining butter in a large pan over a medium heat, add the flour and cook for 1 minute, stirring well to combine. Gradually add the stock, whisking constantly until it thickens. If it goes a bit lumpy, don’t worry; just whisk briskly until smooth. Reduce the heat and simmer for 3-4 minutes. Season well and add the mustard. Stir in the cream, then simmer for a further minute.
4. Add the broccoli and chicken to the sauce and stir well. Transfer the mixture to a 1.5 litre pie dish.
5. On a floured work surface, roll the pastry out to the thickness of a pound coin, making sure it’s large enough to cover the top of the dish. Brush the edges of the dish with a little beaten egg and place the pastry on top. Brush the pastry with beaten egg. Use a sharp knife to make a small hole in the centre of the pastry to allow the steam to escape, then cook in the oven for 30-35 minutes until the pastry is puffed and golden.