Preheat oven to 375 degrees F. Prepare Pastry for Single-Crust Pie. On a lightly floured surface, roll out pastry to a circle about 12 inches in diameter. Line a 9-inch foil pie pan with pastry. Trim pastry to 1/2 inch beyond edge of pie plate. Fold under extra pastry. Crimp edge as desired. Do not prick pastry. Sprinkle the 3/4 cup chocolate pieces over bottom of pie shell.
For filling, in a bowl, combine eggs, corn syrup, brown sugar, butter, coffee liqueur, flour, and vanilla. Stir in the pecans. Slowly pour filling over chocolate pieces in crust, spreading evenly.
Cover edge of pie with foil to prevent overbrowning. Bake for 25 minutes. Remove foil. Bake about 10 minutes more or until edge is puffed and a knife inserted near the center comes out clean. Cool on a wire rack. If desired, drizzle pie with melted chocolate. Cover and chill within 2 hours. Attach recipe for Coffee Whipped Cream (below).
Pastry for Single-Crust Pie
In a bowl, stir together flour and salt. Using a pastry blender, cut in shortening until pieces are pea-size. Sprinkle 1 tablespoon cold water over part of flour mixture; toss gently with a fork. Push to side of bowl. Repeat with additional cold water, 1 tablespoon at a time until all is moistened. Shape into a ball.