Preheat oven to 120C. Butter a 25cm round cake tin (not springform) and line the bottom with a circle of buttered baking paper.
While it's cooling beat the eggs with the remaining 70g of sugar until quadrupled in volume. Add the chocolate to the eggs and beat slowly until combined. Pour into the prepared tin. Put a folded teatowel in the bottom of a deep baking tray and enough hot water to come 3/4 of the way up the tin. Bake for 50 minutes* or until set. Leave the cake to cool in the water before refrigerating.
Bring to room temperature before serving. I sprinkled the cake with rose flavoured Persian fairy floss and a few rose petals, and served with a dollop of thick cream, to which I'd added a few drops of rose water. To serve, slice with a hot knife wiped clean between each cut.
* I don't have a 25 cm tin or a baking dish big enough to hold one, so I used a 23cm one. My new oven is so much quicker than any I've ever used so the smaller cake took the same time as the bigger one in the recipe despite being deeper. Another oven may take a bit longer...note that the recipe I referred to in the original post says bake a 23cm cake for an hour and a half.
Happy birthday Pauline!