Preheat the oven to 200C/400F/Gas 6. Roll out the pastry and use it to line a 9in/23cm fluted flan tin. Bake blind for ten minutes and allow to cool.
Put the pears into a pan with the water, 50g/1¾oz of the sugar, the cloves and the lemon rind. Bring to the boil, cover, lower the heat and simmer for ten minutes. Remove the pears from the liquid and allow to cool. Discard the liquid.
Melt the chocolate in a bowl over a pan of simmering water. Add the butter and combine. Set aside.
In a pan, heat the remaining sugar and golden syrup over a low heat until the sugar has dissolved. Bring to the boil, then lower the heat and simmer for two minutes.
Whisk the egg into the chocolate mixture until combined. Now add the syrup mixture then stir in the vanilla extract and the nuts.
Place the pears flat side down on a board. Make lengthways cuts all along each pear, taking care not to cut all the way through. Put the cut pears into the pastry case.
Pour the chocolate and nut mixture into the flan case.
Bake for 25-30 minutes until the filling is set.