Make Crust: Grease a 9-inch square cake pan. In a sauce pan combine the butter, sugar, cocoa, egg and vanilla. Cook over medium heat stirring constantly, until smooth and slightly thickened. Stir in the remaining crust ingredients and press into prepared pan.
Make the creamy center: cream the butter and gradually beat in icing sugar and egg. Spread over crumb mixture and chill for about 15 minutes.
Make the chocolate topping: melt the chocolate and butter together over hot water or in a microwave, being careful not to burn. Spread on top of the previous parts. Chill until set. Cut into squares with a sharp knife.
* No-bake, 3-layer (chocolate covered) bars - Nanaimo bars are a traditional Canadian dessert, though nobody is certain where the tradition came from. Laura Secord is a Canadian candy company; their cook book says this about the origin of these fattening delicacies:
"A version of these no-bake bars developed in the Canadian kitchens of a well-known food company, was christened by them Nanaimo bars after the city of that name on Vancouver Island. Nanaimo (from sne-ny-mo, a local Indian term for a loose confederation of five bands) started as a Hudson Bay Trading Post in 1849."