Peel and segment the orange with a paring knife, removing the membranes and white pith. Chop the segments and toss with the orange liqueur in a bowl; set aside for about 10 minutes.
Spoon the lemon curd into a small liqueur glass or brandy snifter in an even layer. Top with a thin layer of whipped cream, then pile on the oranges and dollop with the remaining whipped cream. Sprinkle with crushed shortbread cookies, if desired.