Bake the pie crust, unless you are using a graham cracker crust.

In a small saucepan, melt the chocolate over low heat. Remove it from the heat and let it cool.

Meanwhile, in an electric mixer, cream the butter.

Gradually add the sugar and blend until creamy.

Mix in the cooled chocolate and the vanilla.

Add the eggs, 1 at a time, beating for 5 minutes after each addition on medium speed until the mixture is very light and fluffy.

Turn the filling into the cooled, baked pie crust. Chill it for 1 to 2 hours in the refrigerator.

Serve it topped with whipped cream, chocolate shavings, and crushed walnuts, if desired. Cover and refrigerate any remaining pie.