Preheat oven to 450 degrees F. Prepare dough for Pastry for a Single-Crust Pie. On a lightly floured surface, use your hands to slightly flatten dough. Roll dough from center to edge into a 12-inch circle. Wrap pastry circle around rolling pin; unroll into a 9-inch pie plate. Ease pastry into pie plate without stretching it. Trim pastry to 1/2 inch beyond edge of pie plate. Fold under extra pastry even with edge of plate. Crimp edge as desired.
Line pastry with a double thickness of foil. Bake in the preheated oven for 8 minutes. Remove foil. Bake for 6 to 8 minutes more or until golden. Cool on a wire rack. Reduce oven temperature to 325 degrees F.
Sprinkle caramel bits into bottom of the baked pastry shell. In a small saucepan combine chocolate, butter, and peanut butter; cook and stir over medium-low heat until melted and smooth. Remove from heat.
In a large bowl whisk together eggs, brown sugar, flour, whipping cream, liqueur, vanilla, and salt. Add chocolate mixture; whisk just until combined. Stir in peanuts. Pour over caramel bits in crust.
To prevent overbrowning, cover edge of pie loosely with foil. Bake in the preheated oven for 30 minutes; remove foil. Bake for 20 to 25 minutes more or until filling appears set in center. Cool completely on a wire rack. If desired, serve with ice cream.
Pastry for Single-Crust Pie
Stir together all-purpose 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 edges 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. Do not prick pastry. Bake as directed in individual recipes.