about 1 cup
2 (1-ounce) squares unsweetened chocolate
3 tablespoons water
1/2 cup sugar
Dash of salt
1/4 cup plus 2 tablespoons butter or margarine, softened
1/2 teaspoon vanilla extract
Combine chocolate and water in top of a double-boiler; cook over boiling water until chocolate melts. Add sugar and salt; cook an additional 5 minutes. Stir in butter and vanilla.