In a small microwave-safe bowl, melt unsweetened baking chocolate in 30-second intervals, until melted. Stir after every 30 second interval. Set aside to cool.
In a saucepan, blend sugar, and eggs over medium heat with a whisk. Cook until an instant-read thermometer reads 160 degrees, stirring constantly.
Remove egg mixture from heat. Add the melted chocolate to the egg mixture, whisk until blended thoroughly. Add vanilla extract. Set aside to cool for 1 to 2 hours, or until room temperature.
Using a hand mixer in a large bowl, beat butter on high speed until light and fluffy (about two minutes.) Blend in cooled chocolate, and continue beating on high speed for an additional five minutes. Scrape the sides of the bowl occasionally using a silicone spatula. When the butter and chocolate are entirely incorporated, set aside.
In a separate large bowl, whip the heavy whipping cream until it reaches a soft peak stage. Take the whipped cream and add it to the chocolate mixture. Fold in the whipped cream until the two mixtures are thoroughly blended.
Pour the chocolate mixture into your prepared pie crust and refrigerate overnight, or until set. Top with additional whipped cream. Enjoy!
Use chocolate shavings or curls as a garnish.