Preheat oven to 300 degrees and grease one 10 inch round cake pan.
In a small saucepan combine the water, salt and sugar over medium heat and cook until completely dissolved. Set aside.
Melt the bittersweet chocolate in a double boiler or in a microwave in intervals. Be careful not to overheat the chocolate or it will seize up. Pour the chocolate into the bowl of an electric mixer.
Cut the butter into pieces and beat the butter into the chocolate one piece at a time. It helps if the butter is soft here. Beat in the hot sugar-water. Let the batter cool slightly. It just needs to be cool enough that when you add the eggs they don't scramble. Slowly beat in the eggs, one at a time.
Pour the batter into the prepared pan. Place pan in a larger pan with edges for a water bath. Fill the larger pan with boiling water halfway up the sides of the cake pan. I used the hot water from my double boiler.
Bake cake in the water bath at 300 degrees for 45 minutes. Don't overbake. The center should still look wet. Chill cake overnight in the pan. When ready to serve, dip the bottom half of the pan in hot water to loose the cake and invert it on the serving plate.
The cake is dense and truffle-like. Serve with cream and berries.