In a large mixing bowl, beat the eggs and caster sugar until light and fluffy.Sift in the plain flour, cocoa powder, and baking powder. Gently fold the dry ingredients into the egg mixture until well combined.Pour the batter into a lined and greased baking tray, spreading it evenly.
Place the baking tray in the preheated Airfryer Oven and bake at 180 degrees Celsius for 9 minutes or until a toothpick inserted into the center comes out clean.Once baked, carefully remove the sponge from the oven and allow it to cool completely.
In a heatproof bowl, combine dark chocolate, milk chocolate, unsalted butter and double cream. Then heat them up and stir well, then set them aside to cool down.
Carefully spread a layer of cream on the cooled sponge. Roll the sponge tightly from one end to the other to create a log shape. Drizzle as much ganache as possible on top.You can also decorate with additional Christmas-themed elements like powdered sugar for a snowy effect, or small festive decorations.