Hi Nigella Team! My best friend of 37 years has always been a huge fan of those chocolate lime, boiled sweets (the ones with lime on the outside and a a chocolate centre). I bake regularly for him and his family and, with his birthday coming up in April, wanted to do him a surprise cake this year. What better than a chocolate lime cake? He's a huge fan of Nigella's Lemon-Syrup Loaf Cake (Domestic Goddess, p13) and I wondered if there was any way of converting that into a chocolate lime drizzle? Otherwise, any other ideas you might have would be very welcome. Cheers!
It should be possible to convert the Lemon-Syrup Loaf cake to a chocolate and lime version by using lime zest and juice in place of the lemon zest and juice and you could swap 30g (3 tablespoons) of the flour for 30g (3 tablspoons) cocoa poder. However cocoa tends to suck up quite a lot of moisture so we would also suggest increasing the milk in the batter from 4 to 5 tablespoons (please note though that we have not tested this). If you have a mini loaf pan then you could also make small versions of the loaf cakes (for directions see the recipe on p242 of Domestic Goddess).
One idea that you may like to consider are to make a chocolate lime version of Nigella's Key Lime Pie (Domestic Goddess p103). The introduction to the recipe suggests adding a teaspoonful of cocoa to the digestive biscuit base to get the chocolate lime sweet effect. You could also make a chocolate lime sandwich cake by making a 2 layer chocolate sponge cake (the Old Fashioned Chocolate Cake from Feast, p269) then fill it by spreading over some softened mascarpone and a good layer of lime curd (for a recipe see Domestic Goddess, p344). Dust the top with some icing sugar and you could add some shards of pared lime zest for extra colour.