In a small saucepan, melt the chocolate on low heat. watch closely to make sure it does not burn. Put the chocolate in a bowl to cool.
Cream the butter and sugar, scraping the bowl to ensure it is completely combined.
Beat in cooled chocolate and vanilla until well blended.
Add eggs one at a time, mixing for 4 minutes between each addition. I know this is a lot of mixing but it makes for a light, fluffy, and smooth filling.
Pour into cooled pie crust.
Combine cold heavy cream, vanilla, and powdered sugar into bowl. You can use a stand mixer or hand mixer. Beat until stiff peaks form.
Spread whipped cream onto chocolate filling. Top with chocolate curls if desired. Chill at least 3 hours before serving.