cook a little for a few minutes. Add the milk a little at a time stirring continuously. Allow all the milk to be absorbed into a smooth mixture before adding some more. By not adding all the milk at once you avoid getting lumps later. To construct the pie, roll out the pastry and cut into two equal sized rectangles of pastry which will form the base and top of the pie. Place the first rectangle of pastry on a well greased baking tray. Brush some beaten egg on the pastry boarder then take the second rectangle of pastry and lay onto of the pie filling aligning with the pastry base. Then using a fork press down along the edges of the pie. Put a few slits in the top of the pastry.