4 sq. unsweetened chocolate
1 c. sifted confections' sugar
3 tbsp. hot tap water
1 egg
4 tbsp. butter

Melt chocolate in top of double boiler (hot but not boiling, lowest setting on stove). When melted lift off top of boiler - let chocolate cool a minute - add the sugar and 3 tablespoons hot water. Beat well. Add butter - 1 tablespoon at a time. Beat well until smooth and creamy. Spread on cooled cake.