In medium saucepan, over low heat, stir condensed milk, butter or margarine, and cocoa until the butter melts and mix is warm; remove from heat.
Stir in eggs, flour, vanilla, and chopped nuts; pour into prepared pie crust. Sprinkle top with remaining 1/4 cup walnut halves.
Bake at 350 degrees F (175 degrees C) for 50 minutes or until center is firm. Serve warm or cold garnished with fudge sauce, whipped cream, and a strawberry, if desired.
