Minute-Boil Fudge Frosting
["2 oz. chocolate, finely cut", "1 1/2 c. sugar", "7 Tbsp. milk", "2 Tbsp. shortening", "2 Tbsp. butter", "1 Tbsp. corn syrup", "1/2 tsp. salt", "1 tsp. vanilla"]
["Bring slowly to full rolling boil, stirring constantly.", "Boil briskly 1 minute (1 1/2 minutes on a rainy day).", "Cool and add 1 teaspoon vanilla and beat until thick.", "A rotary beater may be used.", "Frost the cake before the frosting becomes too thick."]
["chocolate", "sugar", "milk", "shortening", "butter", "corn syrup", "salt", "vanilla"]