Have all the ingredients at room temperature.
Put the chocolate in the top pan of a double boiler set over but not touching simmering water in the bottom pan. Stir until the chocolate is melted and smooth. Let cool to room temperature.
In the bowl of an electric mixer fitted with the flat beater, combine the confectioners' sugar, butter, the 6 Tbs. milk, the vanilla and salt and beat on low speed until combined, about 1 minute. Stop the mixer and scrape down the sides of the bowl. Increase the speed to medium and beat for 2 minutes, then reduce the speed to low. Add the chocolate and beat until combined, then increase the speed to medium and beat for 1 minute more.
If the frosting is dry, add more milk, 1 tsp. at a time, until it is creamy but still holds peaks. Makes about 4 1/2 cups.
by The Savvy Kitchen