I think this is amongst my favourites. It's so rich and dense a tiny piece is more then enough. Serve with fresh fruit for a real tasty treat. This reminds me of the flourless chocolate cake I've eaten in restaurants.
I use Xylitol because it isn't chemically altered like those other low cal sweeteners you can buy at the grocery store.
Preheat your oven to 300'F. Preheat to 325'F if you live at high altitudes. Get your kettle out and fill it up. Boil the water. You will also need a pan bigger then your 9" spring form for a bain-marie.
Grease the spring form pan. I used non-stick spray oil on mine. Wrap the spring form pan in one piece of tin foil so that none of the water from the bain-marie leaks into it. If you use a solid cake pan then the tin foil isn't necessary. But do be ultra careful when filling the pan with the hot water that none splashes onto the chocolate cake.
In a small sauce pan over medium heat, combine the water, salt and powdered xylitol. Once again if you live at high altitudes, cut back on the sugar. Once this is done make sure that you stir the mixture to dissolve all the xylitol. Set aside.
Melt the chocolate in the top of a double boiler. Just make sure the water doesn't touch the bottom of the top pot because it can easily scorch the chocolate as it melts.
Pour the melted chocolate into a large bowl of an electric mixer.
Cut your butter into small pieces and add one at a time as you beat the chocolate. Make sure all the butter is well incorporated into the chocolate mixture. The beat in the hot sugar water.
Slowly beat each egg into the mixture, making sure all the egg is well combined.
Pour the batter into your prepared cake pan. Set it into a larger pan and put it into the oven. Pull the oven shelf out and slowly and carefully pour the boiling water from your kettle into the bottom of the bigger pan. I filled mine 3/4 full to ensure the cake would cook properly. You can fill it 1/2 full if you don't have enough water, that will work too.
Bake the cake in the water bath for 45 minutes. The middle might seem a tad liquid but not to worry it should set up as it cools. I let mine sit on a metal cooling wrack on my counter for about an hour, then put it into the fridge over night to cool.
If you wish to unmold the whole cake, dip it in hot water for 10 seconds and the invert on to a plate. You can also freeze this cake. If you do cut it in individual pieces then freeze it. You can freeze the whole thing if you wish. To thaw leave in the fridge for several hours before serving. Small pieces are best since this is a very dense rich cake.