To make the bars easier to slice straight from the freezer ... you may omit the salt in the recipe. Keep your keto chocolate ...

For this recipe you will need a 23x30cm/9x12in traybake ... Add all the remaining sponge ingredients, except the chocolate chips. Using an electric hand whisk, mix until light and fluffy.

They also help to make chocolate crackles — my childhood favourite ... I find this easier to slice if you do so before it sets too firmly. You could also spoon this into paper cases.

Nigella Lawson has her very own twist on rocky road chocolate bars, declaring: "Out go the Rich Tea biscuits and in come Amaretti," referring to the delicious ingredients in her own recipe.