Make a sabayon: combine egg yolks, eggs, and sugar (1) in a mixing bowl. Whisk on high speed until light and fluffy (ribbon stage), then reduce to low speed to refine air bubbles. Prepare a meringue with egg whites and sugar (2), whip to medium peak. Gently fold the meringue into the sabayon, then fold in flour and cocoa powder, followed by melted butter, until fully incorporated. Bake at 180°C for 12–15 minutes, or until fully cooked.