In a heavy small saucepan, melt butter and chocolate over low heat, stirring frequently. Cool 20 minutes.
Meanwhile, prepare and roll out pastry. Line a 9-inch pie plate with pastry; trim and crimp edge.
In a mixing bowl, combine eggs, sugar, flour and vanilla. Stir in the chocolate mixture and chocolate pieces. Pour into pastry-lined pie plate.
Bake pie in a 350 degree F oven about 55 minutes or until filling is evenly puffed and edges of filling are slightly cracked. Cool on wire rack (center will sink slightly as pie cools). Serve with whipped cream. Makes 10 servings.
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 the mixture; gently toss with a fork. Push moistened dough to the side of the bowl. Repeat moistening dough, using 1 tablespoon cold water at a time, until all the dough is moistened (4 to 5 tablespoons cold water total). Form dough into a ball. On a lightly floured surface, use your hands to slightly flatten dough.