01 - Preheat oven to 350°F.
02 - In a bowl, mix chocolate cookie crumbs, melted butter, and sugar until combined. Press firmly into the bottom and up the sides of a 9-inch pie dish.
03 - Bake crust for 8–10 minutes. Let cool completely.
04 - Melt chocolate gently over a double boiler or in the microwave, stirring until smooth. Let cool slightly.
05 - In a large bowl, beat butter and powdered sugar until pale and fluffy, about 2 minutes.
06 - Add melted chocolate and vanilla extract; beat until well combined.
07 - Add eggs one at a time, beating on medium-high speed for 3–4 minutes after each addition, until silky and glossy.
08 - Spread chocolate filling evenly into cooled crust.
09 - Cover and refrigerate for at least 4 hours, or until set.
10 - Just before serving, whip cream with powdered sugar and vanilla until soft peaks form.
11 - Spread or pipe whipped cream over the pie and garnish with chocolate shavings if desired. Slice and serve chilled.