Ingredients

• 3 squares unsweetened chocolate 
• 1/4 cup white sugar 
• 3 tablespoons cornstarch 
• 1 teaspoon instant coffee 
• 1/4 teaspoon salt 
• 1 egg 
• 3/4 cup water 
• 2 cups sifted icing sugar 
• 1/2 cup butter or margarine 
• 1 teaspoon vanilla extract 

Melt chocolate in the top of a double boiler. Pour in a smooth mixture of the next 5 ingredients. Cook and stir until thick and smooth. Stir a little of the hot mixture with the egg, and return to double boiler. 
Cook and stir 3 minutes. Cool completely. 
Meanwhile, cream icing sugar with butter or margarine until light. Add vanilla, and beat in chocolate custard. Refrigerate until completely cold and butter or margarine starts to stiffen. If necessary add additional sifted icing sugar to make a spreading consistency. Fill layer cake, and swirl remaining icing over top and sides. Chill cake before serving to firm the icing. 

YIELD: 
Enough for layer cake and filling