Combine the chocolate and butter and melt over very low heat, stirring constantly. In a mixing bowl, combine the confectioners sugar, salt, milk, and vanilla. Beat until well combined. Add the butter mixture and beat until smooth. If the frosting is too thick, thin with a little more milk added a teaspoon at a time. If the frosting is too thin, allow it to stand for a few minutes, stirring occasionally. Once the frosting is the right consistency, work quickly as the frosting becomes hard on standing.

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