Combine first 5 ingredients, stirring until ingredients are blended. Stir in melted chocolate morsels and walnuts.
Fit piecrust into a 9" pieplate according to package directions. Fold edges under, and flute. Spoon filling into piecrust.
Bake at 375° for 30 minutes. Cool completely on a wire rack. Serve with coffee ice cream, and, if desired, Heavenly Fudge Sauce.