12 ounces 70%b chocolate
2 sticks unsalted butter
1 cup superfine sugar
1. Heat the oven to 300%deg;F
2. Using extra butter, grease a 10-inch round cake pan and line with baking parchment.
3. Break the chocolate into pieces and melt with butter in a bowl over simmering water. Beat the eggs and 5 tablespoons of the sugar in an electric mixer until the volume quadruples.
4. Heat the remaining sugar with 7 tablespoons of water until dissolved into a light syrup. Pour the hot syrup into the melted chocolate and cool slightly.
5. Add the chocolate to the eggs and beat slowly until the mixture is combined. Pour into the pan.
6. Put a folded dish towel in the bottom of a roasting pan. Put in the cake and add enough hot water to come three-quarters of the way up the side of the cake pan.
7. Bake in the oven for 1 hour until set. Leave the cake to cool in the water before unmolding.