Instructions

1. First make the caramel by boiling the tins of sweetened condensed milk in water. Place the unopened tins in a pan and cover with cold water. Bring to the boil and keep simmering. Top up with more water every so often to ensure that the tins remain completely immersed in water. After 2.5 hours remove the pan from the heat and allow the tins to cool in the water.
2. Preheat the oven to 180c and grease a tin. I used a 32cmx22cm tin.
3. Mix the flour and sugar together in a bowl and rub in the butter until it reaches the consistency of breadcrumbs.Tip the mixture into the tin and press down with the back of a spoon until it is all even and level. Bake for 20 minutes in the oven and leave to cool in the tin on a wire rack.
4. Once the caramel and biscuit base have cooled, pour the caramel onto the biscuit and smooth with a spatula. Chill in the fridge for 20 minutes.
5. Melt the milk and white chocolate separately in bowls over a pan of boiling water. Pour the milk chocolate over the caramel and then swirl in the white chocolate to create a marble effect.
6. Decorate with chocolate stars (you may want to mark on the chocolate the outline of where you will cut the shortbreads to do this neatly. Simply run a knife through the melted chocolate).
7. Leave to cool before cutting into squares to serve. If you are short on time and want to cool the chocolate in the fridge, I would recommend removing it before the chocolate is completely set, otherwise it will be very difficult to cut.