This fudgy frosting will keep for two weeks in the refrigerator.
1 In a saucepan on very low heat, carefully melt the chocolate and butter, stirring constantly. Add the corn syrup, sugar, and milk. Increase heat to medium-high, bring to a boil, and cook for 5-8 minutes, stirring only occasionally, until the mixture becomes a candy-like, gooey fudge. Remove from heat and stir in vanilla. Let chill to spreadable consistency.