Take the eggs out from the fridge ahead of time or soak them for a few minutes in a bowl of warm water.
Preheat the oven to 170 degrees C (338 degrees F).
Butter and flour a 20 cm (8 inch) pan, or spray it with baking spray.
Put the eggs and sugar in the bowl of your stand mixer.
Beat the eggs until very fluffy and pale yellow (about 15 minutes on medium/high speed). To test that it has been beaten enough, let some of the mixture fall into the bowl; if it remains "sitting" on top, that means that it's ready.⏱ 15 min
Sift the flour and cocoa powder on top of the egg mixture, a little at a time, and fold it gently with a wooden spoon, from bottom to top.
Pour the batter into the prepared pan. Don't smooth the top or bang the pan on the counter; leave it as it is!
Bake for 40 minutes or until a toothpick inserted into the center comes out clean. (Don't open the oven for the first 20 minutes!)⏱ 40 min
Turn off the oven but leave the chocolate Italian sponge cake inside for at least 10 minutes so it can cool down slowly (put a wooden spoon in the oven door to keep it slightly open). After that, remove it from the oven, let it cool for 10 more minutes, loosen around the edges with a knife, and then flip the cake on a wire rack upside down (without the pan) to cool completely.
Enjoy!