1 lb. high quality bittersweet choc, finely chopped
3 oz. high quality unsweetened choc, finely chopped
½ cup + 2 Tablespoons strong brewed coffee
6 large eggs at room temp
¼ cup sugar
1 cup whipping cream, whipped to soft peak (until it dollops nicely and hold its shape when dropped from a spoon)
Preheat oven to 325F. Lightly butter the inside of a 10 inch round cake pan. Line the bottom pan with parchment paper or wax paper. Melt choc with coffee over simmering water bath. Meanwhile whisk together eggs and sugar. Also whisk over water bath until mixture is warm to the touch and sugar is dissolved. Place in mixing bowl and whip until tripled in size, reduce speed and whip for another 2 minutes.
Fold egg mixture into choc mix 1/3 at a time, and then fold in whipped cream in same manner. Transfer to prepared pan and tap the pan lightly on work surface to settle any air pockets. Smooth top.
Place pan in a larger baking pan and put in enough hot water to come ½ way up the sides of the cake pan. Bake for 50-60 minutes releasing any steam in oven about ½ way through. Cake should be somewhat firm in the middle. Turn oven off and let cake cool in oven for 2 hours. Carefully un-mold cake on to serving plate. Cut cake with a hot knife.