Firstly, make the pastry. Do this by softening the butter in a food processor, but do not cream it. Add in the icing sugar, then the flour and finally the egg yolks and the water. Mix until all combined. One you have your ball of pastry, wrap it in cling film and place in the fridge for 30 minutes. After half an hour, roll out your pastry and place it in your flan dish. Bake blind at 180°C/gas mark 4 for 15 minutes. Remove the baking beans and cook for a further five minutes. Remove from the oven and leave to cool. To make the chocolate ganache filling, place a saucepan of water on the hob to boil. Break the dark chocolate into a bowl and add the butter. Place the bowl over the saucepan of boiling water to melt. In a separate pan, bring the double cream and glucose to the boil. Once boiled, pour the cream onto the melted chocolate mixture and whisk until very smooth. Pour the chocolate filling into the pre-cooked pastry tart base. Allow to set at room temperature for approximately four hours. Serve with candied oranges and crème fraiche.