Prepare the meringue by whisking the eggwhites. If they become a little stiff add the cornflour, the lemon, salt and sugar and whisk until stiff peaks.
Fold the chopped hazelnuts and the cacaonibs through it.
Make a shape on a baking tray covered with baking paper. Round is easiest. Make sure it is not too thin and create some uneven peaks on the surface. Whatever you like.
Put in the oven and turn the temperature down to 120˚C (248˚F) immediately
How long it needs cooking is a little bit depending on the thickness of your layer but check after 45 minutes if it is not becoming brown. The outside should feel firm. Leave to cool and remove carefully from the baking tray
Make the ganache by heating the cream in a saucepan. Don't let it boil but close to the boil
Break the chocolate into pieces and stir the hot cream through it. Stir until smooth. Put the ganache in a piping bag with a small nozzle and decorate the meringue with it.