We will begin by making the yolk, for this we pour the water into a saucepan and add the sugar; cook for five minutes and remove from the fire. We put the yolks in a bowl and mix them with the cornstarch. Return the saucepan to the heat, add the egg yolk preparation and cornstarch and cook, stirring constantly, until it thickens slightly. Remove from heat, let cool, stirring the yolk from time to time.
To make the cake, we separate the whites from the yolks. Transfer the latter to a bowl, add the sugar and beat them with a whisk until they are creamy and whitish.** Whip the egg whites until stiff** with an electric whisk, and add them to the previous mixture, mixing with enveloping movements. so they don’t lose volume. Add the sifted flour with the yeast and salt, little by little, gently integrating it.
Grease with butter a removable mold of 20 cm in diameter and sprinkle it with a little flour.
Pour the dough and bake the cake for about 30 minutes in a preheated oven at 180°. When it is warm, we unmold it on a rack and let it cool.
We put the very cold filling cream in a bowl. Add the sugar little by little and beat it with an electric whisk, until it is very firm. We divide it into two equal parts and mix a part with the pure cocoa. Stir gently with a spatula until it has a uniform color. We reserve this truffle and the whipped cream in the fridge.
For make the light syrup cook 100 ml of water with icing sugar. Then we pour the brandy and continue cooking for a few more minutes, until it is reduced. Remove from the heat and let it cool down.
Cut the cake in half, horizontally. Line a flat round service plate with parchment paper, we can help us with a pastry ring with an acetate strip inside. To assemble the cake we begin by placing a sponge disk, brush it with part of the syrup. Add a layer of whipped cream, reserving a little for decoration.
We freeze the cake for half an hour so that the layers do not mix. Once the time has passed, add a layer of truffle and cover with the other sponge disk, brushing it again with the syrup.
We remove the ring and the acetate strip that surrounds the cake. We distribute the yolk coverage on the surface, smoothing it with a spatula. Sprinkle with a few tablespoons of sugar and lightly burn with a torch kitchen.
Introduce the cream that we had reserved into a pastry bag with a curly nozzle. We form some rosettes on the surface of the cake.