Ingredients for 6 people:
1) Take a large bowl, and separate 6 eggs. Beat the egg yolks together with 180 grams of sugar and 1 sachet/1 teaspoon of vanilla.
2) Whisk for 5-10 minutes until the mixure is light and fluffy. Meanwhile, in another bowl, mix 60 grams of sugar with 2 tablespoons of bitter cocoa and add everything to the yolks.
3) Stir well to prevent lumps from forming. In another bowl, beat the egg whites with a pinch of salt until stiff and then fold them into the egg yolks. Use a spatula or large metal spoon, mixing from top to bottom so as not to dismantle the mixture and knock out all the air in the whisked egg whites.
1) Take a 22-24 cm cake pan with high edges. Prepare it with a light coating of butter and a dusting of flour before pouring in the chocolate mixture. Cook the sponge cake in a preheated oven at 180° for 35-40 minutes.
2) Once it’s cooked, take it out of the oven and leave it to cool on a pastry rack. When it's still warm, you can serve the chocolate flavoured cake as it is or cut it in half and stuff it with the custard and fruit to taste.
You can also fill puffs, profiteroles, puff pastry canons and many other cakes with this custard. The flour makes it more consistent, but a little less delicate.
In a saucepan, work the egg yolks with the sugar using a wooden spoon. Add the flour little by little, without stopping stirring until the mixture is blended. Pour in the boiling milk a little at a time, always stirring, and add a little vanilla or lemon zest to taste. Place on the heat, continue to stir, simmer for 3-4 minutes.
Pour the cream into a bowl and let it cool down by turning it from time to time, so that skin does not form on the surface.