For the pastry tarts; Place the flour, butter, and sugar into a food processor and blend until the consistency looks like fine breadcrumbs. Slowly, while the machine is still running, pour in the water and allow the mixture to come together.
Remove pastry and work into one ball of dough on a floured surface. Roll out the dough to a thickness of 4mm and cut circles with a 5cm or 2 inch cutter.
Press the circles into petit fours or mini muffin tins, making sure they reach up the sides of the moulds. Refrigerate overnight if possible or at least 2 hours.
Preheat oven to 180 degrees.
Place a square of greaseproof paper in each shell and fill with baking beans or dry rice. Bake blind for 10 - 15 minutes.
Remove the rice and paper, brush with beaten egg and bake another 5 minutes until pastry is golden brown.
For the filling: melt the chocolate and the cream in a bowl over a pot of simmering hot water. Turn off the heat leaving it to stay warm until needed.
Cream the sugar and the butter until very pale about 5 minutes on high speed with an electric beater.
Fold in the melted chocolate with a metal spoon until well combined then pour into the pastry cups and refrigerate until set.
For the meringue; preheat oven to 180 degrees C. Put the sugar and the water into a small pot and bring to the boil; leave to simmer for 2 minutes.
Meanwhile beat the egg whites with an electric beater until they form stiff peaks.
Slowly pour in the sugar syrup while still beating. This partially cooks the whites insuring that they only need to be finished quickly in the oven. Keep the beater going until the mixture has cooled; pipe onto the chocolate filling.
Bake in oven for 5 minutes.
Serve immediately if you like the chocolate to be warm or refrigerate for a truffle centre.