In a small saucepan, stir the cut-up chocolate and shortening over low heat until melted. Remove pan from heat. Using a clean small paintbrush, brush the inside (bottom and sides) of each phyllo shell evenly with the melted chocolate mixture. Return each shell to plastic tray included in package. Chill phyllo shells in refrigerator about 20 minutes or until chocolate is set.
Meanwhile, in a small bowl, stir together the cream cheese, sour cream, and powdered sugar until smooth. Stir in liqueur or milk. Transfer mixture to a small resealable plastic bag; seal bag. Snip off a corner of the bag. Pipe about 1 teaspoon of the cream cheese mixture into each shell. Cover tarts loosely; chill 2 to 4 hours.
If desired, garnish each tart with a fresh raspberry and mint leaves. Makes 15 tarts.