Is there any reason why you cannot use Malibu instead of coconut essence in the icing for the Tropical Chocolate Cake?
Nigella's Tropical Chocolate Cake (from FEAST) is a chocolate and pineapple cake that is slathered with a coconut-flavoured meringue icing. The icing uses coconut essence as it has a stronger coconut flavour than Malibu (a coconut-flavoured white rum). You would need to use quite a bit of Malibu in the icing to get a strong coconut flavour and this extra liquid could upset the consistency of the icing too much.
For the cake you don't have to use Malibu and if you use the juice from the canned pineapple instead then you could add a teaspoon of coconut essence as well, if you have bought coconut essence specifically to make the cake. You can always try adding 2 teaspoons of Malibu to the icing but we feel that it doesn't flavour the icing enough to be truly tropical.