Preheat oven to moderate, 180°C. Lightly grease an 18 x 28cm slice pan. Line with baking paper, extending paper 2cm above pan edge.

Prepare Topping; (see recipe below).

Meanwhile, in a small bowl, using an electric mixer, beat butter and sugar together until light and fluffy. Stir in flours, in 2 batches, until a firm dough forms. Press dough evenly into prepared pan. Bake for 10 minutes. Cool.

To make Filling; in a small saucepan combine sweetened condensed milk, butter and syrup. Heat on medium, stirring until smooth. Continue stirring, for 3-4 minutes, until mixture bubbles and thickens.

Spread Filling over base. Grate Topping over filling. Bake for 10-15 minutes, until firm. Cool in pan for 15 minutes before transferring to a wire rack to cool completely. Cut into fingers. Dust with icing sugar.

Sift flour and cinnamon together into a small bowl. Stir in sugar. Rub in butter, using fingertips, until mixture resembles coarse breadcrumbs.

Add water and bring mixture together into a dough. Roll dough into a log. Wrap in plastic wrap and chill in the freezer for 30 minutes, until firm.