Sift the flour, baking powder and cocoa powder into a bowl, add the sugar and mix everything together. Add the eggs and beat with a whisk. When the mixture is smooth, add the chopped hazelnuts and melted (well cooled) butter, and continue stirring. Grease the cake tin with butter, dust it with flour and pour in the mixture. Level the surface and bake in a preheated oven, at 160-170 °C, for 25 minutes. Take the cake out of the oven and let it cool down. Using a large knife (preferable a serrated one, such as a breadknife) slice it into 3 disks. Lay the first 2 upside down on the work surface and spread the mascarpone on the bottom one (the base of the cake). Place the middle disk on top and, using a spatula, distribute the chocolate spread over it, then cover with the third disk. Now prepare the glaze: heat the chocolate (broken into pieces) with the oil in a small saucepan, in a bain-marie on the stove. Stir and when it is completely melted, pour it over the cake: drizzle it slowly into the centre and it will gradually spread out over the entire surface. Sprinkle with the flaked almonds over the cake and leave it to cool down until the glaze has set.
It’s an absolutely mouth-watering cake that keeps well in a cool place for at least a couple of days.