Preheat the oven to 180c fan. On a lightly floured surface, roll out the pastry to fit a 3cm deep, 22cm diameter tart tin. Trim the pastry to fit the tin. Place a piece of baking parchment on top of the pastry and fill the centre with raw rice.

Put the tin on a baking tray and bake for 10 minutes. Carefully remove the paper and rice, prick the base with a fork and return to the oven for 7-8 minutes until lightly brown and cook the pastry through. Leave to cool then carefully remove from the tin and place on a serving plate.

For the filling, break for white chocolate into pieces and place in a heatproof bowl. Melt in a bain-marie. Spoon 2 tbsps of the melted chocolate onto a clean board and spread thinly, then leave in a cool place to set (do not chill). Keep the remaining melted chocolate on the water to keep warm.

Meanwhile, cut the gelatine into small pieces and put in a small heatproof bowl. Cover with cold water and leave to soak for 5 minutes. drain off the water using a sieve and put the soaked gelatin back in the bowl. Spoon over 3 tbsps of very hot water and stir until thoroughly melted.

Mix the hot gelatin liquid into the bowl of warm melted chocolate until thoroughly blended. Remove the bowl from the water and leave to cool for 10 minutes.

Make up the egg white powder according to the pack instructions and whisk until thick and foamy. In another bowl, whip the cream until it thickens but is not too firm.

Using a spatula, scrape out the egg white and whipped cream into the melted chocolate mixture. Add the vanilla extract and then gently fold the ingredients together until thoroughly blended. Spoon the mixture into the pastry shell and chill for at least 1 hour until set.

To serve, using a teaspoon, scrape the chocolate on the board to make shards and small curls. Scatter over the tart and serve.