Place the butter and water in a saucepan over high heat and bring to the boil.

Remove from the heat and stir in the flour and salt until a smooth dough forms.

Turn the dough out onto a lightly floured surface and knead until smooth and elastic.

To make one large pie, split the dough into two with one a little larger than the other. The larger one will be the base of your pie, the smaller one the top. Roll base into 2mm thickness and transfer into a lightly greased pie dish. Add pie filling.

Roll top into 2mm thickness and transfer onto the top of the pie. Press the edges to seal and trim the excess pastry. Use a small, sharp knife to cut a slit in the top of the pies.

Brush with the egg and cook for 30–35 minutes or until the pastry is cooked through and golden.