Preheat oven to 160ºC Grease and flour 23 cm square pan. Melt chocolate and butter in large saucepan over low heat, stirring constantly (do not be concerned if the white chcolate separates). Remove from heat when chocolate is just melted. With electric mixer, beat in eggs until mixture is smooth. Beat in flour and vanilla. Spread batter evenly in prepared pan. Sprinkle almonds evenly ove the top. Bake 30-35 minutes or just until set in center. Cool completely in pan on wire rack. Cut into 5 cm squares.