Place the chocolate, cream, butter and sugar in a medium saucepan over low heat. Cook, stirring with a metal spoon, for 5 minutes or until the chocolate melts and the mixture is smooth. Transfer to a large bowl. Set aside for 5 minutes to cool slightly.
Preheat oven to 150C. Brush a round 22cm (base measurement) cake pan with melted butter to grease. Line the base and side with non-stick baking paper. Lightly whisk the egg yolks in a small bowl. Add egg yolk and vanilla to the chocolate mixture. Stir until well combined. Stir in the almond meal. Sift the flour, baking powder and cocoa over the chocolate mixture. Stir until combined.
Use an electric beater to beat the egg whites in a clean, dry bowl until soft peaks form. Add a large spoonful of egg white to the chocolate mixture. Fold until well combined. Fold in remaining egg white. Pour into the prepared pan and smooth the surface.
Bake in oven for 40-45 minutes or until the surface of the cake is firm to the touch. Set aside in the pan for 20 minutes to cool before turning onto a wire rack to cool completely.
Dust with cocoa powder and top with fresh berries. Serve with whipped cream.