Melt first 3 ingredients in top of a double boiler. Add egg and stir to cook and thicken Remove from heat. Stir in crumbs, coconut and nuts. Press firmly into an ungreased 8 X 8 pan.
Cream butter, cream, custard powder and icing sugar together well. Beat until light. Spread over bottom layer.
4 squares semi-sweet chocolate (1 oz. each)
2 tablespoons unsalted butter
Melt chocolate and butter over low heat. Cool When cool, but still liquid, pour over second layer and chill in refrigerator.