Cook in the middle of the oven for 20-25 minutes or until lightly golden.
Leave to cool (partly, if you’re impatient) before proceeding to the caramel layer.
For the Caramel Layer
Gently heat the sugar and butter in a non-stick frying pan, stirring until melted together.
Add the condensed milk and bring to a rapid boil, stir continuously and do not take off the heat. Add the vanilla extract after 4 minutes, then continue for 1 additional minute.
Take off the heat and pour the mixture over the shortbread layer. On a flat surface, shake the tin a little to get the caramel to evenly distribute.
Chill in the fridge until set.
For the Chocolate Layer
Break the chocolate up in to small chunks and melt in a bowl over hot water until smooth.
Allow the chocolate to cool very slightly for a minute, and then pour on top of the caramel.
Chill in the fridge until fully set before cutting in to pieces.

Notes

– The shortbread layer can be made by crushing 250g of shop bought shortbread biscuits and combining with 55g of melted butter.
– If you’d prefer a softer caramel layer, reduce the boil time of caramel mixture to 1-2 minutes.
– For a swirl effect chocolate layer, additionally melt 50g of white chocolate and swirl on top of the dark chocolate.
– Wellington Square can be kept at room temperature or refrigerated. I like to keep mine in the fridge to keep the caramel firm!