Heat the cream the day before and remove from the heat. Chop 200 grams of chocolate, dissolve in the cream and chill overnight. For the dough melt Nutella and chop the rest of the chocolate.
Beat the eggs and icing sugar with the whisk of the hand mixer until creamy. Slowly add oil and Nutella and mix. Mix flour, cornstarch and baking powder and stir into the dough. Stir in chocolate.
Spread the dough on a greased and breadcrumbed frying pan. Bake in the preheated oven (electric oven: 175 °C/ gas: level 2) for 30 minutes and let it cool down. Whip the chocolate cream with the whisk of the hand mixer until creamy and spread on the base.
Dust with cocoa and icing sugar. Makes 40 pieces. Decorate with cream tuffs and hazelnut kernels just before serving.