Preparation

• Preheat the oven to 170 °C, with heat from top and bottom, for at least 30 minutes before baking to ensure an even temperature.
• Sift the flour (or the flour blend), along with the cocoa powder, if using, to avoid lumps.
• Place a saucepan of water on the stove over medium-low heat to prepare a bain-marie.
• In a large bowl, add whole eggs, yolks, sugar, and a pinch of salt.
• Place the bowl over the saucepan of the bain-marie and, while the eggs warm up (caution: they should only get slightly warm, to prevent cooking), whisk them with electric beaters (or by hand) until you see that there is no liquid egg left at the bottom of the bowl.
• Then remove the bowl from the heat and continue whisking the eggs at high speed until they triple their initial volume. With an electric whisk, this will take about 12-15 minutes exactly; you can set an alarm on your phone to ensure you do it for the necessary time. Note: If you prefer not to complicate things, whisk the eggs cold for as long as needed until they triple in volume.
• Add the sifted flours in three batches, gently folding them in with a spatula to incorporate well without losing volume.
• Line the bottom of the baking pan with parchment paper to prevent sticking.
• Grease the pan with butter and lightly flour it to facilitate unmolding.
• Fill the pan evenly with the prepared batter.
• Bake at 170 °C for about 30-35 minutes, placing the tray at the bottom of the oven to ensure even cooking.
• Once out of the oven, leave the mold on a wire rack until it cools completely before unmolding.
• When it is completely cold, wrap it with clear plastic wrap and let it rest until the next day to improve the texture.
• The next day, you can cut it to fill it with the desired filling.