Directions

1. Step 1 Heat the oven to 180C/160C fan/gas 4. Lightly grease and line a 20-22cm square or rectangular baking tin with a lip of at least 3cm.
2. Step 2 To make the shortbread, mix 250g plain flour and 75g caster sugar in a bowl. Rub in 175g softened butter until the mixture resembles fine breadcrumbs.
3. Step 3 Knead the mixture together until it forms a dough, then press into the base of the prepared tin.
4. Step 4 Prick the shortbread lightly with a fork and bake for 20 minutes or until firm to the touch and very lightly browned. Leave to cool in the tin.
5. Step 5 To make the caramel, place 100g butter or margarine, 100g light muscovado sugar and the can of condensed milk in a pan and heat gently until the sugar has dissolved. Continually stir with a spatula to make sure no sugar sticks to the bottom of the pan. (This can leave brown specks in the caramel but won't affect the flavour.)
6. Step 6 Turn up the heat to medium high, stirring all the time, and bring to the boil, then lower the heat back to low and stirring continuously, for about 5-10 minutes or until the mixture has thickened slightly. Pour over the shortbread and leave to cool.
7. Step 7 For the topping, melt 200g plain or milk chocolate slowly in a bowl over a pan of hot water. Pour over the cold caramel and leave to set. Cut into squares or bars with a hot knife.