Cook pie crust according to instructions (i.e. bake at 400 degrees for about 12-15 minutes until golden brown) and let cool completely.
In small bowl, combine gelatin with cold water. Let stand for about 2 minutes. Add boiling water and stir until the gelatin is fully dissolved and the mixture is clear. Set aside and let cool slightly.
In a large bowl, mix sugar and cocoa. Add whipping cream and vanilla and beat on medium speed until mixture is stiff. Pour in gelatin mixture and beat until well blended.
Spoon into crust. Refrigerate for at least 3 hours. Garnish with whipped cream and/or chocolate shavings. (Recipe for homemade whipped cream linked below.)