1.Make poached pears.
2.Meanwhile, process flour, polenta, sugar and butter until crumbly. Add egg; process until ingredients come together. Knead dough on a floured surface until smooth. Wrap dough in plastic wrap. Refrigerate 45 minutes.
3.Grease a 24cm (9½-inch) loose-based flan tin. Roll pastry between sheets of baking paper until large enough to line tin and about 4mm (¼-inch) thick. Ease pastry into tin, press into base and side; trim edge, reserve trimmings. Refrigerate 30 minutes. Roll reserved trimmings between sheets of baking paper into a 30cm (12-inch) square, place on oven tray; refrigerate.
4.Preheat oven to 180°C.
5.Make custard filling.
6.Place pears in pastry case. Carefully pour in custard filling. Use a pastry cutter or knife to cut 1.5cm (¾-inch) wide strips from remaining pastry. Weave pastry strips to form a lattice on top of tart. Press ends on edge of flan tin to seal; trim edge. Sprinkle top with nuts. Place tart on an oven tray.
7.Bake tart 45 minutes or until golden. Stand tart in pan 15 minutes. Dust with sifted icing sugar; serve with syrup.
8.Cut each pear into eight wedges. Place remaining ingredients in a large saucepan; bring to the boil. Add pears; simmer, covered, 15 minutes or until almost tender. Cool in liquid. Drain pears; reserve liquid. Discard thyme and rind. Return reserved liquid to pan; simmer, uncovered, 5 minutes or until syrup thickens slightly.
9.Whisk ingredients in a large jug.
Serve with thick (double) cream or vanilla ice-cream.
This tart is not suitable to freeze.Note