Line a baking sheet with greaseproof paper and lay one sheet of pastry on top. Spread with the mustard then add the ham in an even layer, leaving a 1cm border all the way round the edge. Scatter over the cheeses, then top with the second sheet of pastry. Seal the border all the way round using a fork then egg wash the entire parcel. Bake for 25 minutes and leave to cool for 5 minutes before cutting into 8.