Cooking oil spray, for greasing
1 cup plain flour
¼ cup icing sugar mixture
100g chilled butter, chopped
1 egg yolk
1 Tbsp chilled water
Extra plain flour, for dusting
80g golden syrup
80g butter, chopped
2 x 395g cans sweetened condensed milk
Ice-cream, to serve
Preheat oven to 180C. Grease an 18cm fluted tart tin with cooking oil spray and line with baking paper. Put flour, icing sugar mixture and chilled butter in a food processor and pulse until mixture resembles fine crumbs. Add egg yolk and water. Pulse until mixture just comes together. Turn out onto a lightly floured surface and gently knead until smooth. Shape dough into a disc and wrap in plastic wrap. Refrigerate for 30 minutes to rest.
Roll out dough between 2 sheets of baking paper until 5mm thick. Line prepared tin with dough and trim edges. Cover with plastic wrap and refrigerate for 30 minutes or until firm.
Meanwhile, put golden syrup and butter in a medium saucepan over a medium-low heat. Once butter melts, add condensed milk. Cook, stirring constantly with a wooden spoon, for 10 minutes or until golden and thickened. Pour into pastry shell. Using the back of a spoon, smooth surface.
Bake for 10 minutes, then transfer to a wire rack and allow to cool to room temperature. Refrigerate tart for 2 hours or until chilled. Serve with ice-cream.