To prepare the sponge cake, pour the eggs into the bowl of a planetary mixer, add 210 grams of granulated sugar and 1 pinch of salt. Whip at high speed for about 10 minutes: you will have to obtain a soft and swollen mixture

Sift the 00 flour into the egg and sugar mixture.

Mix the mixture with a spatula, making delicate movements from bottom to top so as not to disassemble it.

Line a 20cm diameter round cake tin with parchment paper. Pour 1/5 of the dough into it. It is preferable that the pan can be opened, but you can also use a normal pan.

Bake in a preheated static oven at 180° for 10 minutes, placing the pan on the central shelf. Remove from the oven and leave to cool.

Proceed in the same way for another 4 times, obtaining a total of 5 thin discs of sponge cake. Leave to cool completely.

Pour the hazelnuts into the glass of a mixer and blend them finely at intervals of about 10 seconds, for 1 minute, until you obtain a flour. It is important to blend a few seconds at a time to avoid the risk of burning the mixer.

Add the cocoa and icing sugar, blending for a few more seconds.

On a work surface, break up 450 g of dark chocolate, 250 g of milk chocolate and 50 g of white chocolate. Transfer all the chocolate to a large bowl suitable for bain-marie cooking. The bowl must be glass or steel.

Put a pot of water on the stove and heat it over medium-high heat. Place the bowl on the sides of the pot and melt the chocolate, stirring constantly.

When the chocolate has completely melted, remove the bowl from the heat and turn off the heat. Add the hazelnut flour to the bowl with the chocolate and mix well.

Then add the milk at room temperature and mix everything until you get a smooth cream

Finally add 100 g of butter at room temperature, divided into small pieces. Mix with a spatula until everything is combined.

To prepare the syrup, pour 200 ml of water and 80 g of granulated sugar into a thick-bottomed saucepan. Turn the heat to high and let the sugar melt. When the sugar is completely dissolved, add the rum, turn off the heat and let it cool to room temperature.

When all the individual preparations are cold you can compose the dessert.

Place the first of the 5 discs on a plate and moisten it with the freshly prepared syrup, using a kitchen brush.

Cover the entire surface with a layer of cream and repeat the operation covering with another layer of sponge cake, wet and cream. Continue in the same way until all the ingredients are finished, then place the dessert in the refrigerator for at least 1 hour.

Inside a glass, preferably with a spout, add 300 g of dark chocolate and 50 g of butter. Melt everything in the microwave, blasting it for a few seconds at a time, stirring often.

Take the cake out of the refrigerator and, using kitchen shovels, transfer it to a rack. Under the grill, place a pan or plate, which will be used to collect the icing. Pour the icing over the cake starting from the center, covering the entire surface and edges.

Place back in the fridge for about ten minutes.

Collect the glaze poured on the tray and pour it, together with the remaining glaze in the glass, into a sac-à-poche with interchangeable nozzles. With a size 5 round hole nozzle, make the wording “Savoia”. With a weaving nozzle, make the upper edge of the cake. Finally, decorate the lower edge with an open star nozzle.

Let the cake rest in the refrigerator for at least 15 minutes before serving.