Glaçage au Chocolat

• 3 oz. semi-sweet chocolate
• 3 tablespoons dark rum, preferably Martinique rhum vieux

To make the icing, put the chocolate into the top of a double boiler, over hot water, with the rum, and cook, stirring, until the chocolate is smooth. Remove from the heat, but do not take the chocolate off the hot water. Using a wire whisk, beat in the butter, a tablespoon at a time. Place the mixture over cold water, and continue to beat until it is cool. Allow to stand until it is thick. Spr