Introduce the eggs, water and oil into a mixer with kneader attachment, then add the Fantasy Cake mix and work at medium speed for 3-4 minutes until an even dough is formed. Divide the dough into 2 portions and add the bitter cocoa to one part. Place the 2 doughs into the special mould, alternating light and dark, until three-quarters full. Bake in a static oven at 175-180°C for 35-45 minutes (450 g pieces).