Preheat the oven to 160 C / Gas 3. Grease a baking tray. Place all base ingredients into a bowl and mix until smooth.
Press mixture into the base of baking tray and prick with a fork.
Bake in the preheated oven until golden, 30 to 40 minutes. Set aside to cool.
For the topping: place butter, sugar, golden syrup and condensed milk into a saucepan and stir over a low heat until melted. Bubble gently for 5 to 8 minutes, stirring until thick and fudge-like. Pour gently over shortbread evenly and leave to cool.
Melt the chocolate, pour over the toffee and leave to set. Cut into squares and store in an airtight container. Enjoy :)