Preheat oven to gas mark 6 roll out the pastry and use to line a 20cm flan tin. Chill for 20 minutes. Prick the base with a fork and lay baking paper on this and some dry baking beans. Bake for 10 minutes. Take off paper and beans.
Reduce oven temp to gas mark 3. Break chocolate into squares and put in a bowl with the butter. Stand over a pan of simmering water, making sure base of the bowl does not touch the water, stir until smooth and all melted.
Whisk the eggs sugar coffee essence and flour until mixed whisk into the chocolate mixture. Pour into the flan case and bake tfor 25- 30 minutes until set. Leave to cool.
Place sugar and water in pan and heat gently until dissolved, simmer for 2 minutes.
Cut the Clementine’s into slices and drop into the syrup simmer for 5 minutes or until the rind looks translucent lift out and allow to cool on a plate.
Arrange on top of the tart just before serving.
Heat the marmalade, orange juice and sugar stirring until sugar is just dissolved.
Mix corn flour with water and stir into juice and marmalade mix, heat until simmering pour into a jug add Cointreau, leave to cool.