Preheat oven to 300º.
Grease one 9" round cake pan (or glass pie plate) and set aside.
NOTE: Cut a piece of parchment paper into a circle with "handles" and place in the bottom of pan. Grease pan with parchment paper in it.
In a small saucepan over medium heat combine water, salt and sugar. Stir until completely dissolved then set aside.
Melt chocolate chips and pour into a bowl.
Cut butter into 1Tbsp. pieces and beat into chocolate, one piece at a time.
Mix in warm water/sugar mixture until combined.
Slowly beat in eggs, one at a time, until completely smooth
Add vanilla and mix until just combined
Pour batter into prepared pan.
Put the cake pan in a larger pan and fill larger pan with boiling water until it reaches halfway up the sides of cake pan, being careful not to get water into cake! HINT: Put pans in oven before adding water.
Bake in water bath for 45 minutes. Center will still look wet but edges will look done.
Remove from water bath and let cool on wire rack.
Chill cake overnight ( or for at least 6 hrs.)
Carefully lift parchment paper out of pan and the cake with it. Remove parchment paper. Put on serving plate and sprinkle with powdered sugar. Serve with fresh berries, ice cream, etc.