4 oz ghirardelli semi-sweet chocolate
4 tablespoon butter
3 cup powdered sugar
1/3 cup hot milk
1 teaspoon vanilla
1/8 teaspoon salt
In heavy saucepan on low heat, melt broken chocolate with butter, stirring constantly. Beat sugar with milk, vanilla, and salt until smooth. Add melted chocolate and beat until thick enough to spread on cake.
Source: Ghirardelli Chocolate Company