1.Preheat oven to 350 Butter 9 inch springform pan, dust with small amount of cocoa. Heat butter with 1/4 cup of cream over medium heat, until butter melts. Add chocolate and stir till melted, remove from heat. Beat eggs and sugar and cocoa powder. Beat in chocolate mixture Pour batter into pan and bake 35-40 minutes, until puffed and set. Let cool 1 hour, run knife around edge before release pan.

2.Topping: Beat cream and sour cream and confectioners sugar until soft peaks form.

3.Dust cake with confectioners sugar and serve with whipped cream