Line a baking sheet with nonstick baking paper. Cut 6 strips of nonstick baking paper, each 30 x 5 cm (12 x 2 inches). Roll up a strip and place inside a 6 cm (2½ inch) pastry cutter set on the baking sheet. Open out the strip so it lines the cutter.
Melt the chocolate over a pan of simmering water (see
Beat the cream cheese in a bowl to soften it. Beat in the cream, yogurt, sugar, orange rind and juice and liqueur, if using. Cut 1 flaky chocolate bar lengthways into shards and reserve the best pieces for decoration. Crumble the trimmings and the remaining 3 flaky chocolate bars into the creamed mixture.
Spoon the mixture into the chocolate cups and freeze for at least 3 hours. Carefully peel away the paper cases and transfer the cups to the refrigerator for about 1 hour before serving. Alternatively, return the cups to the freezer for a later date. Serve the cups decorated with shards of flaky chocolate bar and strips of candied orange peel.