In a large mixing bowl, mix together the granulated sugar, butter and brown sugar with a mixer or a whisk. Beat in the eggs and mix until well incorporated, about 1 minute. Stir in the melted chocolate, bourbon and vanilla. In a small bowl, sift together the flour, cocoa and salt; fold the flour mixture into the egg mixture. Pour into the pie shell and bake until set, 30 to 40 minutes. Let cool to room temperature.
For the whipped cream: In a stand mixer, whisk the heavy cream on medium speed until peaks begin to form. Add the confectioners' sugar, bourbon, vanilla and cream of tartar. Continue to whisk until the cream begins to hold medium firm peaks.
Spread the whipped cream over the pie and garnish with chocolate shavings.