The cake is fine and delicate, so it must be handled with care both before and after baking.
Melt the chocolate in a bain-marie. Once the chocolate has melted, remove from the heat and refrigerate. It should drop in temperature but still remain liquid.
Mix the egg yolks with half the sugar until they double in volume. Add the melted and cooled chocolate and stir gently.
Whip the egg whites with a pinch of salt. Add the remaining sugar and mix until the sugar has completely melted. Incorporate the egg whites into the chocolate mixture in 3 batches. Each time, fold them in gently with upward movements.
Preheat the oven to a medium heat. Line a 25/35cm (10/14 inch) baking tray with parchment paper. Pour the mixture into the tray and level it – this will be a thin layer. Bake for 15-17 minutes, until lightly browned around the edges.
Remove from the oven and cover with parchment paper. Leave like this until it has completely cooled.
When cooled, turn the cake upside down. Carefully remove the baking paper from the bottom of the cake. Cut into two equal pieces, 25/17cm (10/7 inch).
Chocolate truffle cream: Bring the whipping cream and pear juice to almost boiling point. Turn off the heat and add the chocolate and vanilla. Let them rest for 2 minutes then stir well until smooth. Leave to cool.