preheat the oven to 140C/275F/Gas 1. Line a baking tray with greaseproof paper.
Whisk the egg whites in a clean bowl until soft peaks form when the whisk is removed.
Whisk in the sugar
a spoonful at a time
until all of the sugar has been added and stiff peaks form when the whisk is removed.
Whisk in the cornflour and vinegar.
Spoon the meringue mixture onto the baking tray in a large circle.
Bake in the oven for 10 minutes
then switch the oven off and leave in the oven for 2-3 hours
or preferably overnight
until crisp
but uncoloured.
Remove the meringue from the oven and set aside to cool completely
then place onto a serving plate.
Meanwhile for the caramelised nuts
heat the oil in a deep heavy-based frying pan until a breadcrumb sizzles and turns brown when dropped into it. (CAUTION: hot oil can be dangerous. Do not leave unattended.)
Heat the sugar and water in a separate saucepan until the sugar has dissolved.
Add the nuts and bring the mixture to the boil. Continue to cook until the temperature of the sugar syrup reaches 110C/225F (use a sugar thermometer to check this).
Remove the nuts from the syrup using a slotted spoon and carefully lower them into the deep fat fryer. (CAUTION: The nuts are coated in a liquid that may spit upon contact with the oil. Stand well back and keep your face and hair away from the deep fat fryer.) Fry for 1-2 minutes
or until golden-brown
then remove from the oil using a slotted spoon and set aside to drain on kitchen paper. Sprinkle with sea salt flakes.
For the filling
melt the chocolate in a bowl set over a saucepan of boiling water. (Do not let the base of the bowl touch the water.)
Smooth the melted chocolate over the cooled meringue.
