Preheat oven to 375F.
Place homemade or store-bought pie crust into pie plate or round pan. Set aside.
In a small saucepan, combine unsweetened chocolate and unsalted butter. Bring to a boil.
Immediately remove from heat. Set aside to cool.
Once cooled, whisk in beaten eggs, sugar, vanilla and salt. Omit salt if using salted butter.
Whisk continuously for approx. 45-60 seconds to combine ingredients and incorporate air into the batter.
Once the batter has been mixed thoroughly, pour into prepared pie crust.
Bake for approximately 20-25 minutes.
Allow to cool for at least 15 minutes before serving to allow inside to set.