1. First of all, bake the nuts at 160C until golden brown, before blitzing them up in a food processor.
2. Whisk together the egg yolks and ¾ of the sugar.
3. Then whisk together the egg whites and the remaining sugar.
4. Fold the egg whites into the egg yolk and sugar mix then fold in the blitzed nuts and the baking powder.
5. Pour the mixture into a buttered and greaseproof lined tin and bake in the oven at 160C for 20 -30 minutes, then take out and allow to cool.
6. For the topping, you need to roast the hazelnuts, place them on a tray and bake at 180C for 5-6 minutes or until golden brown.
7. Put the water in a pan and add the sugar, heat over a medium heat until the sugar has dissolved then turn up the heat and gently bubble for 4 minutes or until you have a light caramel.
8. Take off the heat and add the toasted nuts.
9. Immediately pour onto a baking tray that is lined with greaseproof paper. Allow to set and then remove from the paper and break up to use as a garnish.
10. Whip the cream stiffly.
11. Cut the cooled cake in half and sandwich together with some of the whipped cream, place the cake on a serving plate, cover with more of the whipped cream and break over the caramel praline mixture.