Prepare Baked Pastry Shell. Cool. For caramel layer, in a heavy 2-quart saucepan, melt butter over low heat. Add brown sugar, corn syrup, and half-and-half or light cream; mix well. Cook and stir over medium-high heat to boiling. Reduce heat to medium. Cook and stir for 5 minutes more. Stir in the 1 cup pecans. Pour mixture into pastry shell. Set aside.
For creamy custard layer, in a heavy 1-1/2-quart saucepan, stir together sugar, cornstarch, and salt. Stir in milk. Cook and stir over medium heat until thickened and bubbly. Cook and stir for 2 minutes more. Gradually stir hot mixture into egg yolks. Return mixture to saucepan. Cook and stir until bubbly; reduce heat. Cook and stir for 2 minutes.
Remove from heat; stir in 3/4 cup chocolate pieces until melted. Cool about 45 minutes or until room temperature.
In a 1-cup glass measuring cup, combine cold water and gelatin. Let stand for 2 minutes. Place measuring cup in saucepan of boiling water. Cook and stir for about 1 minute or until the gelatin completely dissolves.
In a bowl, beat whipping cream with an electric mixer on medium speed while gradually drizzling the dissolved gelatin over the whipped cream. Continue beating until stiff peaks form.
Gently stir 1 cup of the whipped cream into custard to lighten mixture. Fold in the remaining whipped cream. Pour over top of caramel layer. Cover and refrigerate 6 hours before serving.
Just before serving, in saucepan, melt 1/4 cup chocolate pieces and shortening; drizzle over pie. Sprinkle with 1/4 cup pecans. Makes 8 to 10 servings.
Stir together flour and salt. Using a pastry blender, cut in shortening until pieces are pea-size. Sprinkle 1 tablespoon of the water over part of the mixture; gently toss with a fork. Push moistened dough to the side of the bowl. Repeat moistening dough, using 1 tablespoon of the water at a time, until all the dough is moistened. Form dough into a ball. On a lightly floured surface, use your hands to slightly flatten dough. Roll dough from center to edge into a circle about 12 inches in diameter. To transfer pastry, wrap it around the rolling pin. Unroll pastry into a 9-inch pie plate. Ease pastry into pie plate, being careful not to stretch pastry. Trim pastry to 1/2 inch beyond edge of pie plate. Fold under extra pastry. Crimp edge as desired. Generously prick bottom and side of pastry in pie plate with a fork. Prick all around where bottom and side meet. Line pastry with a double thickness of foil. Bake in a 450 degree F oven for 8 minutes. Remove foil. Bake 5 to 6 minutes more or until golden. Cool on a wire rack.