Bake pie crust or use a Pillsbury refrigerated crust and make according to package directions for a fully baked crust. Set aside to cool.
Melt the chocolate and set aside to cool completely.
Beat sugar and butter on medium high until light and fluffy, about 6-7 minutes.
Add cooled chocolate and vanilla and beat until incorporated.
Cover and chill filling for at least 20 minutes for the filling to setup and thicken.
Pour filling into cooled pie crust.
Beat whipping cream and powdered sugar with a whisk attachment on medium-high speed until stiff peaks just begin to form. Add prepared whipped topping to top of pie.
You can garnish with shaved bittersweet chocolate as well.