In small microwave-safe bowl, combine semisweet chocolate chips and shortening. Microwave on high (100 per cent power) 1 minute; stir until melted and smooth. If necessary, microwave another 30 seconds.
Tilt bowl slightly; dip top edge of filo cup into melted chocolate. Turn right-side up and shake slightly to encourage drips down side. Repeat with remaining cups and chocolate (there will be leftover chocolate). Set aside on serving plate until chocolate is firm.
To make fanciful chocolate shapes for a garnish, if desired, first line a baking sheet with a sheet of waxed paper. Spoon the remaining melted chocolate from step 2 into a small plastic food-storage bag. Snip off a small tip from one corner of the bag; pipe the chocolate onto the waxed paper-lined baking sheet into stars, fans or swirls . Let stand until the chocolate is firm and the shapes are solid.
In a large microwave-safe bowl, combine the white baking chocolate, milk and the liqueur. Microwave on high (100 per cent) power 1 minute; stir the chocolate mixture until melted and smooth. If necessary, microwave the mixture for another 30 seconds. Set the mixture aside to cool to room temperature, about 15 minutes. Stir in the orange rind.
Fold the thawed whipped topping into the cooled white chocolate mixture. Gently spoon the mousse into a large pastry bag fitted with a large star tip. Pipe the mousse into each chocolate-dipped filo cup just until it reaches the top of the cup. Or, alternatively, spoon 1/2 cup of the mousse mixture into each cup. Refrigerate the filo cups for 1 hour or overnight.
Garnish the filo cups with the chocolate shapes if you made them in step 3 above. Makes 6 servings.