Place the eggs and water in a mixer with whisk, add the Pan di Spagna 50 sponge mix, flour, sugar and cocoa and mix at a low speed to form an even dough. Whisk at high speed for around 10 minutes. Place 700-750g of dough in a 60×40 cm baking tray and bake in a fan-assisted or static oven at 220°C for around 5 minutes.