Salted Chocolate Tart Filling

Asked by H_cargill. Answered on 27th January 2016

Full question

I have made the salted Chocolate Tart and the filling mixture doesn't seem to have thickened enough, even though I stirred it over low heat for 15 mins. when I put it in the jug, it is around 800 ml. It does coat back of spoon but is definitely thinner than I would expect. Should I reheat it or will it thicken.?

Our answer

Nigella's Salted Chocolate Tart (from Simply Nigella and on the Nigella website) has a filling that is similar to an American chocolate pudding (or custard) mixture but is thickened using just cornflour (cornstarch) rather than eggs. The chocolate in the mixture helps the tart to set to a soft but cuttable texture.

The filling includes 500ml (2 cups) of double (heavy) cream plus sugar, chocolate and cocoa and should yield a volume of a bit over 600ml (2 1/2 cups). We are slightly concerned that the volume mentioned is 800ml (3 1/3 cups). This would suggest too much liquid in relation to the cornflour and chocolate and could mean that the filling will not set properly. We suggest measuring the ingredients as accurately as possible. If the filling is too thin then you could try very gently reheating the mixture, without boiling, and whisking in another 1 tablespoon of cornflour that has been mixed with 2 tablespoons of milk. Cook the mixture on a very low heat until it thickens further. You may want to cool a little of the mixture and taste it to ensure that it does not taste of uncooked flour, before transferring it back to the jug. The mixture should coat the back of a spoon and leave a clear trail if you draw a finger through the mixture coating the spoon. This may help the filling to set just enough but as the ratio of chocolate is now lower the filling may set but still be on the soft side. Chill the tart overnight for the best possible set. You may also find that you have too much filling but any excess can be transferred to ramekins, chilled and then eaten with a spoon.