At least six hours before baking the cake, prepare the filling: Melt half the chocolate (227g). Bring to boil 1 cup of the cream.

Pour the cream onto the chocolate and whisk it until smooth, then refrigerate until set.

Turn on the oven to 177°C. Line an 8 inch sponge tin with parchment paper and grease.

Set a pan (large enough to hold a mixing bowl) half full of hot water on the stove; bring the water to a boil.

In a mixing bowl, add the eggs, yolks and sugar and whisk together. Place over the bowl of hot water to allow the mixture to heat up.

Sieve the flour and cocoa and set aside.

Whisk the egg mixture until it doubles in volume and then fold in the butter and flour mixture. Spoon the mix into the cake tin; bake about 20 minutes, or until the sponge springs back when pressed.

Remove from the oven onto a cooling wire and make the topping while the sponge cools.

Melt remaining chocolate. Bring to a boil remaining cream. Pour the cream onto the chocolate and whisk it until smooth and then set aside off the heat.

Slice the sponge into three discs and spread the filling onto the bottom two discs and reassemble. Add the remaining chocolate mix to the hot topping and whisk in.

Place the sponge back onto the cooling wire and ladle the topping over the sponge allowing it to run down the sides. Cool the cake for at least two hours before decorating and serving.