Grease a 9-inch square cake pan.

In a saucepan, combine butter, sugar, cocoa, egg, and vanilla.

Cook over medium heat, stirring constantly, until smooth and slightly thickened.

Stir in graham wafer crumbs, coconut, and chopped walnuts.

Press the mixture into the prepared pan to form the crust.

For the creamy center, cream butter and gradually beat in powdered sugar and egg.

Add desired flavorings and food coloring, if desired.

Spread the creamy mixture over the crumb mixture.

Chill for about 15 minutes.

For the chocolate topping, melt chocolate and butter together over hot water or in a microwave, being careful not to burn.

Spread the chocolate topping evenly over the creamy center.

Chill until set.

Cut into squares with a sharp knife and serve.