1. Preheat oven to 450°F. Prepare Pastry for a Single-Crust Pie. On a lightly floured surface roll pastry into a 12-inch circle. Ease pastry circle into a 9-inch pie plate without stretching it. Trim pastry to 1/2 inch beyond outside edge of pie plate. Fold under extra pastry. Crimp edge as desired. Prick bottom and sides of pastry with a fork. 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.

2. Meanwhile, in a medium heavy saucepan combine 1 cup whipping cream, chocolate pieces, sugar, and butter. Cook and stir over low heat about 10 minutes or until chocolate is melted. Remove from heat. Gradually stir about half of the hot mixture into egg yolks. Return egg yolk mixture to saucepan. Cook and stir over medium-low heat about 5 minutes or until mixture is slightly thickened and begins to bubble. Remove from heat. (Mixture might appear slightly curdled.) Stir in crème de cacao.

3. Place saucepan in a bowl of ice water and let stand about 20 minutes or until mixture stiffens and becomes hard to stir, stirring occasionally.

4. Transfer chocolate mixture to a large mixing bowl. Beat with an electric mixer on medium to high speed for 2 to 3 minutes or until light and fluffy. Spread chocolate mixture in pastry shell. Cover and chill for 5 to 24 hours. To serve, top with whipped cream. If desired, garnish with chocolate curls.

Pastry for a Single-Crust Pie

1. In a medium bowl stir together flour and salt. Using pastry blender, cut in shortening and butter until pieces are pea size.

2. Sprinkle 1 tablespoon of the water over part of the flour mixture; toss with a fork. Push moistened pastry to side of bowl. Repeat moistening flour mixture, using 1 tablespoon of the water at a time, until flour mixture is moistened. Gather flour mixture into a ball, kneading gently until it holds together.

3. On a lightly floured surface use your hands to slightly flatten pastry. Roll pastry from center to edges into a circle about 12 inches in diameter.

4. Wrap pastry circle around the rolling pin. Unroll into a 9-inch pie plate. Ease pastry into pie plate without stretching it.

5. Trim pastry to 1/2 inch beyond edge of pie plate. Fold under extra pastry even with the plate's edge. Crimp edge as desired. Do not prick pastry. Fill and bake as directed in recipes.