Preheat oven to 450 degrees F. Prepare Pastry for Single-Crust Pie. On a lightly floured surface, 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 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, 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 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. Serve with ice cream.
Pastry for Single-Crust Pie
In a medium bowl stir together flour and salt. Using a pastry blender, cut in shortening and butter until pieces are pea-size. Sprinkle 1 tablespoon ice water over part of the flour mixture; toss gently with a fork. Push moistened dough to side of bowl. Repeat with additional ice water, 1 tablespoon at a time, until all of the flour mixture is moistened. Gather mixture into a ball, kneading gently until it holds together.