Preheat oven to 325ºF.
Combine sugar, cocoa, flour and salt in small bowl, set aside.
Combine eggs, dark corn syrup, cream, melted butter, and vanilla in a large mixing bowl with an electric mixer on medium.
Stir in the flour mixture, stirring until smooth. Stir in pecan halves. Pour into pastry shell. Bake for 60-70 minutes or until center is firm to the touch. Cool. Serve if desired with whipped topping.