1.To make pastry, blend or process icing sugar, flour and butter until crumbly. Add egg yolk, extract and water; process until ingredients just come together. Wrap pastry in plastic wrap; refrigerate 30 minutes.
2.Grease a 26cm round loose-based fluted flan pan. Roll pastry between sheets of baking paper until large enough to line pan. Lift pastry into pan, press into base and side; trim excess pastry. Prick base all over with fork. Cover; refrigerate 20 minutes.
3.Preheat oven to 200°C/180°C fan-forced.
4.Place pan on an oven tray. Line pastry with baking paper; fill with dried beans or rice. Bake 10 minutes. Remove paper and beans. Bake a further 10 minutes or until golden; cool.
5.Meanwhile, reserve ¼ cup passionfruit pulp. Strain the remaining pulp, reserving 2 tablespoons of seeds. Whisk cream, sugar and eggs together in a medium bowl; stir in strained passionfruit juice and reserved seeds.
6.Reduce oven temperature to 170°C/150°C fan-forced. Pour egg mixture into pastry case. Bake about 35 minutes or until set. Cool; refrigerate 3 hours or overnight.
7.To make orange mascarpone cream: combine ingredients in a small bowl.
8.Serve tart topped with orange mascarpone cream; drizzle with reserved passionfruit pulp.