2 cups plain flour
2 Tbsp icing sugar
125g butter, chilled, chopped
1-2 Tbsp chilled water
Extra plain flour, for dusting
Cooking oil spray, for greasing
1 eggwhite, whisked
1 cup brown sugar
¾ cup maple syrup
Extra 90g butter
Extra 3 eggs
1½ cups walnut halves
Extra 1 egg, whisked
Icing sugar, for dusting
Note: Allow 30 minutes chilling
Put flour, icing sugar and butter in a food processor and process until mixture resembles fine crumbs. Add egg and chilled water and process until a dough ball forms. Turn out dough onto a lightly floured surface and knead until smooth. Shape dough into a disc and enclose in plastic wrap. Refrigerate for 30 minutes or until firm.
Preheat oven to 200°C. Grease a pie tin with cooking oil spray, then line with baking paper. Roll out dough between 2 sheets of baking paper until 3mm thick. Line prepared tin with dough and trim around edge of tin, reserving excess dough. Line dough with baking paper and add baking weights. Bake for 15 minutes, then discard paper and weights. Brush base and sides with eggwhite and bake for a further 10 minutes or until golden. Set aside to cool.
Reduce oven to 180°C. Put brown sugar, maple syrup and extra butter in a small saucepan over a medium heat. Stir until sugar dissolves and butter melts. Transfer mixture to a bowl and cool for 5 minutes. Add extra eggs and whisk to combine. Fold through walnuts, then pour mixture into tart shell.
Roll out reserved dough between 2 sheets of baking paper until 3mm thick. Using a small leaf cutter, cut out leaves from dough.
Brush pastry edge with extra egg wash. Place leaves on top and brush with egg wash. Bake for 40 minutes or until firm. Dust with icing sugar to serve.