Combine chocolate and butter by melting over low heat, stirring constantly. Beat together egg and sugar. Slowly add to the chocolate mixture, beating well. Stir in flour and nuts. Pour into lightly buttered 23 cm square pan. Bake at 350 degrees about 20 minutes. Cool. Next, prepare the second layer. Cream together butter, powdered sugar, vanilla, and whipping cream. Spread on top of the cooled brownies. Combine the remaining chocolate and butter, and melt over low heat. Pour the chocolate butter over the second layer. Chill until top two layers are firm. Cut into one-inch squares. Makes 36 squares