I made the Salted Chocolate Tart and left it in the fridge overnight, but it hasn't set. Where did I go wrong?
Nigella's Salted Chocolate Tart (from SIMPLY NIGELLA) has a chocolate crumb crust and is filled with a rich chocolate cream. The filling is cooked in a saucepan then cooled slightly and poured into the crust. The filling should set in the fridge, though it has a thick fudge-like consistency rather than being very solid.
If the filling has not set and is still runny then we suspect that it may not have been cooked for long enough. The filling is thickened with cornflour (cornstarch) and chocolate. Cornflour needs to be heated to thicken liquids and usually this happens when a mixture comes to a boil. As the filling mixture contains chocolate it is not a good idea to boil it, as the chocolate will burn, so instead it needs to be cooked over a low temperature for a longer period of time. The mixture is ready when it is thick enough to coat the back of a spoon and if you run your finger through the mixture coating the spoon, the line made by your finger will remain visible. You can also taste a small amount of the mixture (let it cool a little first) and any taste of cornflour should have disappeared. If you are still not sure then you can drop a teaspoonful of the mixture on to a chilled plate and put it in the fridge for 2-3 minutes. If the mixture starts to set after this chilling then it should have been cooked enough. If it is still quite runny then return the pan to the heat and cook again for a further 4-5 minutes before testing again.