Prepare Hazelnut Pastry. 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; transfer to 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. Crimp edge as desired.
In a small bowl, combine the 1 egg, the mascarpone cheese, 1/4 cup granulated sugar, and the vanilla. Beat with an electric mixer on low to medium speed until smooth. Cover and chill for 30 minutes.
Preheat oven to 325 degrees F. Pour mascarpone cheese mixture into crust, spreading evenly. In a medium bowl, combine the 2 eggs, the pumpkin, evaporated milk, 1/4 cup granulated sugar, the brown sugar, Frangelico, cinnamon, ginger, salt, and nutmeg. Slowly pour over mascarpone cheese mixture, spreading evenly.
Cover edge of pie with foil to prevent overbrowning. Bake about 1 hour or until a knife inserted near the center comes out clean. Meanwhile, prepare Glazed Hazelnuts.
Cool pie on a wire rack. Cover and chill within 2 hours. Before serving, sprinkle pie with the glazed nuts. Makes 8 servings.
Preheat oven to 325 degrees F. Place hazelnuts (filberts) in a shallow baking pan. Bake for 10 to 12 minutes or until toasted, stirring occasionally. Rub hazelnuts in a clean kitchen towel to remove skins. Place nuts in a food processor or blender. Cover and process or blend until finely ground.
In a medium bowl, stir together the ground hazelnuts, all-purpose flour, sugar, and salt. Using a pastry blender, cut in butter until pieces are pea-size. Sprinkle milk over part of flour mixture; toss gently with a fork. Push to side of bowl. Repeat with additional milk, 1 tablespoon at a time (4 to 6 tablespoons total), until all is moistened. Shape into a ball. Wrap in plastic wrap; chill about 1 hour or until dough is easy to handle.
Line a baking sheet with foil; butter foil. Set aside. Place 1 cup hazelnuts (filberts) in a shallow baking pan. Bake in the 325 degrees F oven for 10 minutes, stirring once. Rub hazelnuts in a clean kitchen towel to remove skins. Coarsely chop hazelnuts.