Beat the 6 egg yolks with the sugar until fluffy, about 15-20 minutes.
Add the finely ground coffee, grated chocolate, candied lemon peel, and ground almonds, mix well.
Whisk the egg whites to stiff peaks and gently fold into the batter.
Pour into a buttered, floured cake tin and bake slowly (about 160°C) for 45 minutes.
Once completely cool, cut in half twice.
Whip the cream with the sugar, fold in the toasted, ground hazelnuts, and use it to fill and coat the cake - decorate the top with some reserved plain whipped cream set aside before adding the hazelnuts.
Based on: Malatinszky Fanny szakácskönyve (a classic Hungarian cookbook), modernised. Calories and protein are estimated.