Combine first 4 ingredients in saucepan and cook over low heat, stirring constantly, until smooth. Add vanilla. Cool to room temperature. Combine pie crust mix and 3/4 cup chocolate mixture in small bowl. Beat at medium speed until smooth. Divide into 6 equal portions. Press each portion onto bottom of inverted 8-inch cake pan. Cook 2 at a time at 425ºF. for 5 minutes. Trim uneven edges of circles. Run knife under pastry to loosen. Invert onto wax paper to cool. Beat whipping cream until thick, but before soft peaks form. Fold in remaining chocolate mixture. Stack pastry on serving plate, spreading about 2/3 cup cream mixture between each layer. Spoon remaining mixture on top. Sprinkle with chocolate curls. Chill at least 8 hours before serving. Store in refrigerator.