Preheat oven to 375°F, bake pie crust until golden, then cool completely.
Melt chocolate, set aside to cool slightly.
Beat butter until fluffy, add sugar, mix until pale.
Add chocolate, vanilla, and salt.
Add eggs one at a time, beating 5 minutes each.
Spread filling into crust, cover, and chill for at least 4 hours.
Whip cream with sugar and vanilla until stiff peaks form.
Spread whipped cream over pie, garnish with chocolate shavings or cocoa powder.
Slice with a hot knife and serve cold.