1 (9 inch) baked pie shell
1 c. butter
1 1/2 c. sugar
4 oz. unsweetened chocolate, melted and cooled
2 tsp. vanilla
4 eggs

Beat butter with sugar until well mixed. Blend in chocolate and vanilla. Set mixer at medium speed and add eggs one at a time, beating for 5 minutes after each egg. Very important. Do not underbeat. Pour in shell and chill several hours. Top with sweetened whipped cream. Serve small portions as this is very, very rich.