Recipe adapted from the Princeville Hotel via Cathy at eat.at
1 pound good quality butter
1 1/4 pound high quality semi-sweet chocolate, chopped (I used Callebaut)
3/4 cup sugar
7 eggs, at room temperature
2 teaspoons vanilla
Preheat oven to 325º. Prepare a 10 springform pan (or high sided cake pan) by placing a round piece of parchment in the bottom, then greasing the pan. If using a springform, wrap the bottom and up the sides with aluminum foil to prevent water from the ban marie from seeping into the cake while baking.
Melt chocolate and butter in the microwave, stopping and stirring at 30 second intervals till smooth. Set aside and allow to cool.
Whip sugar and eggs on high speed for 5 minutes till the batter reaches the ribbon stage (when you lift up a spoonful of batter, it streams down in a nice thick "ribbon"). Slowly add chocolate with mixer going (you don't want to "cook" the eggs by adding warm chocolate too quickly). Then add vanilla. Pour into prepared pan.
Place pan into a roaster and add hot water into roaster to reach about halfway up the cake pan (making sure not to add past the aluminum foil if using). Bake 40 minutes.
Cake may be made a few days ahead and refrigerated. It also freezes well...just defrost slowly in refrigerator before serving. Serve with whipped cream and fresh berries.