1 Melt chocolate in top of double boiler over hot water. 2 When melted, add sweetened condensed milk; stir, add vinegar, flavoring and nuts. 3 Stir to blend. 4 Pour into parchment-lined, 9-inch square pan. 5 Smooth and chill about 2 hours. 6 Turn onto cutting board, peel off paper and cut into squares. 7 Refrigerate in tightly covered container.