For crust: In a medium bowl, combine flour, 1 cup walnuts, salt, and 1/2 cup butter with a wooden spoon until blended. Press evenly into bottom and up sides of a 9-inch pie plate. Bake in 350 degree F oven about 15 minutes or until lightly brown. Cool on a wire rack. Set aside.

For filling: In a medium saucepan, combine 1 cup granulated sugar and cornstarch. Gradually stir in milk; add unsweetened chocolate. Cook and stir over medium-high heat until thickened and bubbly; reduce heat. Cook and stir for 2 minutes more. Remove from heat. In a small bowl, lightly beat egg yolks with a fork. Gradually stir about 1 cup of the hot filling into yolks. Return egg yolk mixture to saucepan. Bring to a gentle boil; reduce heat. Cook and stir for 2 minutes more. Remove from heat. Stir in 1 tablespoon butter and vanilla. Pour filling into a bowl. Cover surface of filling with plastic wrap. Set aside to cool, about 1 hour

In a medium bowl, beat cream cheese and powdered sugar with an electric mixer until light and fluffy. In a chilled small bowl, beat 1/4 cup of the whipping cream with an electric mixer on medium speed or with a whisk until soft peaks form. Gently fold whipped cream into cream cheese mixture.

Spread cream cheese mixture evenly over bottom of the cooled baked pastry crust. Top with filling. Cover and chill for at least 3 hours or until set.

Before serving, in a chilled medium bowl beat remaining 3/4 cup whipping cream and 2 tablespoons granulated sugar until soft peaks form. Spoon whipped cream over filling. Garnish with grated semisweet chocolate and additional chopped walnuts.

Chill any remaining pie, covered, for up to 1 day. Makes 8 servings.