Mix together castor sugar and flour for base. Melt butter and add
to flour mixture.
Press into a 8" square tin and bake for 20 minutes in a moderate
oven.
Place all filling ingredients into a saucepan and cook on very low
heat till butter is melted. Simmer till caramel color, around 8 minutes.
Pour caramel over base and allow to cool.
Melt chocolate and pour over caramel. Allow to set.