Cut the vanilla pod in half and scrape out the seeds.
Juice the orange into a saucepan and then add the cognac and the brown sugar. Bring this to the boil and then add the prunes, vanilla seeds and pod and the cinnamon stick. Reduce the heat to a simmer and cook the prunes for 10 minutes. Remove from the heat and keep to one side while you prepare the pastry and the frangipane.
Preheat the oven to 180'C.
Make the pate brisee: mix together 250g flour, 180g butter, 1 egg, 60g icing sugar and the seeds from half a vanilla pod in food processor. Pulse until the mixture forms a ball. Remove and roll out between 2 sheets of grease proof paper. Refrigerate for 30 minutes while you make the frangipane.
Roll out the pastry to 5 mm thick and cut a circle 3cm larger than the tart case. Line the tart case with pastry and then weigh down the pastry with 2 layers of cling film and some baking beans. Bake in the oven for 15 minutes and then remove the cling film and beans. Return to the oven and cook for a further 10 minutes until golden brown.
Place the 125g sugar, 125g butter, 125g ground almonds and ½ tablespoon of plain flour in a food processor and mix together. Add the eggs and continue mixing until you have a smooth paste.
Drain the prunes from the liquid and then cut into small pieces.
Fill each pastry case with frangipane and then press in the prune pieces. Take care not to over-fill the pastry.
Transfer to the oven and cook for 25 minutes. The frangipane should be firm to touch and golden brown on top. Trim any excess pastry from the edge of the tarts using a serrated knife.
Once cool, remove the tart case.
Serve the tart with a dollop of creme fraiche.
«Sprinkle the top of the tart with flaked almonds after 20 minutes in the oven for a crunchy finish.»