I have been looking at Nigella's salted Caramel sauce on the website. Can recipe be used as the caramel filling in a caramel shortcake recipe?
Nigella's Salted Caramel Sauce is delicious but we suspect that it may not be suitable to use in the filling for a caramel shortbread (millionaire's shortbread) recipe as the sauce is designed to be pourable and so is on the soft side. It will therefore be difficult to cut the shortbread without the sauce squishing out. We would tend to save it for ice cream, desserts or Nigella's Salted Caramel Martini.
If you are looking for a shortbread recipe then we would suggest trying Roxanne's Millionaire's Shortbread on p.240 of Domestic Goddess. This has an easy method of making the caramel filling in a microwave, using butter, golden syrup and condensed milk. This filling is much thicker and sets more firmly, making the shortbread easier to cut. However please note that power levewls on microwaves vary and so the timings in the recipe are a guideline only. The cooked caramel should be a light golden-brown colour and have thickened slightly.