4 cooked Jerusalem artichokes, roughly chopped
1 tsp chopped fresh chervil
1 garlic clove, crushed
1 tsp chopped fresh parsley
2 Savoy cabbage leaves, blanched and refreshed
2 shallots, finely chopped
1 tsp chopped fresh tarragon
1 tsp Dijon mustard
100ml/3½fl oz chicken stock
1 tsp wholegrain mustard
salt and freshly ground black pepper
1 splash white wine vinegar
100ml/3½fl oz double cream
1 free-range egg, beaten
500g/1lb 2oz puff pastry, divided in two and rolled into 15cm diameter circles
2 poached chicken thighs, meat shredded into large pieces
150g/5½oz cooked ham hock, meat chopped into large pieces and cooking water reserved