Unfold piecrust; fit into 9-inch pie pan. Prebake crust according to package directions. Remove from oven. Lower the oven temperature to 325 degrees F.
Beat together sugar, flour, cocoa powder, butter, eggs and vanilla in medium-size bowl. Spoon into pie shell.
Bake in 325 degree F oven 25 to 30 minutes or until set. Transfer to wire rack to cool completely. Makes 8 servings.