1.Make pastry. Process flour, sugar and butter until crumbly. Add egg yolk and enough of the water, processing until ingredients come together. Knead dough on a floured surface until smooth. Enclose pastry in plastic wrap, refrigerate 30 minutes.
2.Grease a 12-hole (¹/³-cup/80ml) muffin pan. Roll pastry between sheets of baking paper until 5mm (¼-inch) thick. Cut 12 x 8cm (3¼-inch) rounds from pastry, press rounds into pan holes. Prick base of cases well with fork. Refrigerate 30 minutes.
3.Preheat oven to 180°C (160°C fan forced).
4.Bake pastry cases about 12 minutes. Cool.
5.Meanwhile, to make streusel topping, process flours, sugar, cinnamon and butter until combined. Roll dough into a ball, enclose in plastic wrap, freeze about 15 minutes or until firm.
6.Combine apple, golden syrup and cream in a medium bowl, spoon mixture into pastry cases. Coarsely grate streusel topping over apple mixture.
7.Bake pies about 25 minutes. Stand 10 minutes before serving, dust with icing sugar.