Step 1

Preheat oven to 160°C. Brush a square 20cm (base measurement) cake pan with the melted butter to lightly grease. Line the base and 2 opposite sides with non-stick baking paper, allowing the paper to overhang the sides.

Step 2

Use an electric beater to beat the butter and sugar in a medium bowl until pale and creamy. Add the flour and beat until just combined. Use your hands to bring the mixture together to form a ball. Turn onto a lightly floured surface and knead until smooth. Use the back of a metal spoon to gently press the mixture evenly into the prepared pan and smooth the surface.

Step 3

Bake in preheated oven for 15 minutes or until lightly browned. Remove from the oven and set aside for 15 minutes to cool.

Step 4

Place the sweetened condensed milk, golden syrup and 40g of the extra butter in a small non-stick saucepan over medium heat. Cook, stirring constantly, for 5-8 minutes or until the mixture thickens and is a caramel colour (see microwave tip 1). Remove from heat. Spoon the hot caramel over the biscuit base and smooth the surface. Set aside for 30 minutes to cool.

Step 5

Place the chocolate and remaining butter in a small, clean, dry heatproof bowl. Place the bowl over a small saucepan of barely simmering water over low heat (make sure the bowl doesn't touch the water). Use a dry metal spoon to stir gently for 2 minutes or until chocolate melts and is smooth (see microwave tip 2). Pour the chocolate mixture evenly over the caramel filling and smooth the surface with a knife. Place in the fridge for 10 minutes or until chocolate sets. Cut the chocolate caramel slice into 16 pieces to serve.