Butter cake pan. Line with parchment paper, butter again. This ensure the parchment paper stays in place. Make sure the sides are buttered very well. A bottomless pan works best but, a regular cake pan can be used.
Beat whipped cream until soft peaks form (not stiff) and set aside. I did this first and transferred to a separate cold bowl and then used my standing mixer to mix eggs and sugar.
Mix eggs with sugar in bowl and heat over a pan of simmering water, only to room temperature. Beat until quadrupled 15-20 minutes. However if you have a vitamix five minutes is enough.
Melt chocolate and coffee in a bowl over simmering water. Set aside until egg/sugar mixture is ready.
Fold 1/4 egg mixture into melted chocolate, stirring well.
Fold this chocolate mixture into remaining egg mixture and add whipped cream.
Pour into prepared cake pan. Put cake pan into larger baking pan. Pour hot water up to 1 inch of cake pan.
Bake at 350 for one hour. Test for doneness when toothpick comes out clean.
Turn off oven and keep cake in oven for 30 minutes with oven door ajar.
Remove from oven, and rest cake another 30 minutes while still in water bath.
Remove from water bath and allow cake to cool thoroughly before removing from pan.
Serve at room temperature to retain that silky light texture.
You can serve cold, but texture will become much more dense.