Preheat the oven to 180ºC . Grease a 9 X 33 cm baking pan. Melt the chocolate and butter over low heat and set aside to cool slightly. Beat the eggs and sugar together until frothy, then add the vanilla. Slowly pour in the chocolate mixture, blending well. Add the flour and beat until smooth. Fold in the walnuts. Spread in the prepared pan and bake for 25 to 30 minutes. Place the pan on a wire rack and allow to cool completely to cold to the touch before frosting. FUDGE FROSTING: Melt the chocolate over low heat in a medium sized saucepan. Add the sugar, eggs, cream, butter, and vanilla, blending well. Increase the heat and bring to a boil, stirring constantly. Remove from the heat and let cool slightly. Spread over the cooled brownies and allow to set before cutting into squares.