1.Make pastry. pastry Process sifted flour, cocoa, icing sugar and butter until crumbly. Add egg yolk and enough of the water until ingredients just come together when processed. Knead dough on floured surface until smooth. Enclose in plastic wrap, refrigerate 30 minutes.
2.Grease two 12-hole (1½-tablespoon/30ml) shallow round-based patty pans with butter. Roll rounded teaspoons of pastry into balls, press over base and side of holes. Prick pastry all over with fork. Refrigerate 30 minutes.
3.Preheat oven to 180°C (160°C fan forced).
4.Bake pastry cases 10 minutes.
5.Meanwhile, stir chocolate, cream and butter in small heatproof bowl over small saucepan of simmering water until smooth. Cool 15 minutes.
6.Soften quince paste in microwave oven on MEDIUM (75%) for about 20 seconds.
7.Divide paste among pastry cases, top with half of the nuts. Top with chocolate mixture, then remaining nuts. Refrigerate 1 hour.