We made this as a birthday cake for Italy, which celebrated the 150th anniversary of its unification in 2011. Gianduia is a speciality of the Piedmont region and it’s a mixture of ground hazelnuts and chocolate, now mostly seen as the popular spread called Nutella.
Preheat the oven to 200C/400F/Gas 6.
Put the hazelnuts on a baking tray and roast them in the centre of the oven for 10 minutes, giving the pan a shake halfway through, until they are golden brown. Watch them carefully so that they don’t burn. Remove and leave them to cool for a few minutes.
Reduce the oven temperature to 180C/350F/Gas 4.Butter a 23cm/9in springform cake tin and line the base with baking parchment.
Place 200g/7oz of the hazelnuts in a food processor and blend them until they are fairly finely ground. If you blend the nuts to the consistency of fine breadcrumbs, they should work a treat, but leave a few coarser pieces to add texture. Set the remaining 50g/2oz hazelnuts aside.
Put the butter and chocolate in a heatproof bowl and set it above a pan of gently simmering water. Stir occasionally and as soon as nearly all the chocolate has melted, remove the bowl from the pan and continue to let the chocolate melt in the residual heat.
Stir in the ground hazelnuts and leave the mixture to cool for 5 minutes.
Beat the egg yolks and sugar together with an electric hand-whisk for at least 5 minutes until pale and creamy, then stir into the chocolate mixture until thoroughly combined. Wash and dry the beaters well.
In a clean bowl, whisk the egg whites until stiff peaks form – they are ready when you can turn the bowl upside down without the eggs sliding out. Do not over whisk.
Working quickly, stir the hazelnut liqueur, amaretto or orange juice, into the chocolate mixture to soften. Add a couple of tablespoonfuls of the whisked egg whites and stir until thoroughly combined, then gently fold in the remaining egg whites.
Spoon the mixture into the prepared tin and bake in the centre of the oven for 35–40 minutes or until the cake is well risen and firm.
Remove the cake from the oven and leave it to cool in the tin for 30 minutes. Undo the springclip and invert the cake on to a serving plate, then peel off the lining paper and leave it to cool completely.
When the cake is cold, spread it with the chocolate and hazelnut spread and sprinkle with the hazelnuts that you set aside – these can be whole or chopped, whatever you prefer.
