Foolproof Chocolate Frosting - cooking recipe

Ingredients

2 sq. unsweetened chocolate
14 or 15 oz. can sweetened condensed milk
1/16 tsp. salt
1 tsp. vanilla
1 Tbsp. butter

Preparation

Put first three ingredients in top of double boiler. Stir frequently and cook over (not in) boiling water for 8 to 10 minutes or until chocolate melts and mixture is smooth and thick. Remove from heat.